How easy isit for sectors to damage a hard drive?
What also causes it?

So far the things i know to damage movie playback would be.

Bad Fragments - Which can be sorted by defragging, right??
Codecs - Which can just be uninstalled.
Drive over heating - Just buy loads of cooling.
Virus maybe.
Slow computer speed to cause jumpy playback.

Is there anything else?

Also is there anything else that could permanantly make a movies playback different from its original state?

Thanks very much.Although your hard disk is encased in tough protected metal sheet but still it is very sensitive. Bad sectors may be accured due to some virus, intence shock, old hard disk with heavy usage, type of software you use, doing partitioning number of times and so on....

Your movie cannot be played as it must be becasue:
Your player's playback settings, your player quality also the quality of movie you are playing, Video Card, Video card settings (pixels), your VGA shared memory and so on...
DrWahabcheers for the info..

can digital video not wear out like analog can, it will stay as clear until it is reencoded right??

how often shall i do a fix for this hard disk as it is on permanantly??One thing you should check is how much memory you have, speed of access memory (still part of RAM)  Also check for spyware on your computer...also get rid of any codec you may not need or do not use.  Second if you have a lot of stuff on your hardrive or system tray...regardless of your speed of CPU it sucks down virtual memory from windows.  It will run slow or choppy.  Analog is a different format than digital..think of this like a VCR versus a DVD player.  A VCR Tape uses dual layer imaging...this means it plays two pictures on top of one another..picture ends up looking like garbage.  A DVD uses digital interlacing. It uses pixals and mixes them up with colors and then interlaces them to make a picture..It uses 1's and 0's information. No with age it will remain the same unless the file is corrupt..then well back to the drawing board I guess and if the file is corrupt it will start getting problems like blockiness in parts of the movie and total pixelation on some frames..exactly...but sometimes it may not even do that.  Sometimes it wont play except in chunks, and then freezes...think of it as a dvd. If a sector on a dvd is not reading right due to compression.  It will loop.  If a file goes bad especially a digital one...your only hope is to download a new one...or recompress it yourself...sometimes this works out the kinks.  But if it is just a divix file...no possible fix...just remake it or download it.  As for your hard drive get spybot and a really good firewall and virus program.  And defrag it every month or so.  Or before a huge install or after an unistall.   If you are constantly installing, unstalling or downloading, back up the files you want to save and do a complete format.  Do not I repeat do not format a hard drive more than is necessary. Because even that can cause serious issues.thanks would it always be noticably pixelated tho??It can yes. Most of the time you get pixalation..where there is an error tring to read a sector of 1's and 0's.  Try this sometime...get a really cheap dvd movie from the store..something a couple of dollars..or if your from europe Euros or Pounds. Put a small scratches on it...not too deep..It will skip, but before it does it will show pixals. Thanks very much for the reply then so with even avi files, b4 they jump they will go pixelated.

Ive noticed over time that my divx files seem to be worse quality than b4 it might be just me!!!! But in scenes thats filming people far away in the background they have a lot of pixelly round them.. that could be a bad rip.
If its pixelation caused from sectors would it be a different type of pixelation.. a definate noticable type that would smear the graphics all over the screen in blocks and go back to normal after it?

Also ill ask u this while im here too.

After ripping, converting from avi to dvd. from ripping dvd to avi i get this wierd lines when the picture moves fast. Try this now, move your page down really fast and looking at the top there'll be a horizontal line for a split second from where the last page LEFT off. Sometimes this happens it must be to do with memory i hope u know what i mean anyway.. Well after convertin an avi to mpg i get this line of fast movements thru out videos on the computer, what is this its like interlaced i think interlaced is loads of little 1mm lines but this isnt the prob i have here, when issuesl ike this happen the screen moves slowly because the lines are causing it to..

Whats going on here??

Also going back to the prob i had with the external hard drive if i did have data corrupted on it would the freezes be logged in a program called divfix? can the corrupted data be recovered? would deleting the file and getting it again sort the problem out? and no unwritten part of the drive would be corrupted would it or if it could be could that be recovered?
ive already run a program over it from the makers of the HDD's website it does a sector scan.

Sorry if these questions have been answered already its just i just woke up.

thanks 4 all this help!!ne1?? Wow..thats some serious questions..well I will start by saying when ripping..you have to contend with copy-protection now a days..thanks to the hulk issue when someone put it out before the movie came out...HAHA.  Still a bad movie..anyway, those lines could mean that is copyright...It could also mean that you compressed the living heck out it. Divx in my personal view is terrible...Your better off getting the plugins for windows media or real player, quicktime...whatever.  Your probably looking at two factors...One copyright two compression...when both are in play your stuff can look like crap.  Also if you try ripping a dual layer dvd..you are asking for trouble unless your dvd burns or is able to read dual and your software that is ripping it is able to read it..also that could be a factor...The software used to rip it can compress it to death..memory I do not think is an issue.  I think you either have corruption problems or what I have just stated.  As for the next question..You can recover it with proper tools and you know what you are doing...there isnt a push button solution...you have to have a editing program in order to get that sort of thing out.  Divxfix is a good tool when it works, but usually if corrupted it still will either look terrible or not perform at all.  Your best bet is to start all over again..What I do is I make a copy and rename the file and store it on dvd or CD..just in case....But thats with my own CREATIONS...I do not condone ripping unless for educational purposes  
Thanks for your reply, what editting program would i need to perform an error check on the drive?

the drive should be ok though shouldnt it, it wasnt being read though i dont think whilst i unplugged it.

Would scrubbing everything off it temporarily, formatting it, using spinrite to fix sectors on it then putting everything back on it fix the issues if unplugging it has damaged it??

The problem probably isnt your hard drive..its the file itself that is bad..An editing program for the file would be something like Priemer or AfterEffects.  Or even Final Cut Pro for the mac.  You can reconstruct the file this way, takes a long long time, but you can get it too look the way you want.  If you are looking for a hard drive recovery, take it to a tech shop...it is best they do it than you.  It takes a while, and it costs, but if you try it unless you know what you are doing you could do more damage than good.A USB external?  If you did not dismount properly..you could have a serious problem.  All your files could be corupted.  Never ever disconnect a USB/Firewire drive without dismounting properly..you are asking for  a world of pain.  My personal opinion if this is the case...You're screwed..there is no way you can recover files when you do that...at least none I know.  If this isnt the case I would say my opinion is that it can be recovered.  And that what I have stated before still stands. But if you are using an external drive...you just ruined it and it will have to be reformatted.  Becuase you just screwed up other files on the drive as well.                So reformatting the hard drive will help now yeah?

And reformatting will sort out the problem i had on the drive?

Are you sure the drive is screwed i DIDNT stop it in windows but there was nothing being written to it when i stupidly unplugged it..

Ive actually already flicked thru the videos on it and all seem same with no freezes.

I ran it through that divfix program we previously mentioned and that also logged now freezes.

Am i lucky here or are these problems going to get worse as time goes on even if i CONTINUE to do it all right?

I stop the device in windows then unplug the power cable now, is this ok?