Did you try startup repair: http://www.bleepingcomputer.com/tutorials/tutorial148.htmltried that. startup repair did not detect a problem. which is strange, it should be able to detect the error occuring during the vista boot.

but it didn't.

and now i'm back to square one.

can anyone direct me further?I'm out of options here.
Try free support: http://support.microsoft.com/oas/default.aspx?prid=11274&gprid=500921It seems like Google is seldom a friend when searching for botched SP1 installations, regardless of which STAGE it HAPPENS.  You'll see a lot of incidents, but seldom any solutions...

Given the time and headache, I'm wondering if it's better just to back up your data, format, then IMMEDIATELY install Vista SP1 afterward.

Granted that doesn't explain WHY it happened, but at least it GETS you back up and running.

I wouldn't try a repair-install at this point.  Your files are on SP1, and repair-installing would cause even more problems trying to bring the OS back to RTM stage.  I agree, Jason.

I can help you with your backing-up process, but I strongly suggest you completely reinstall Vista (like I suggested many times before )

ummmm...errrrr......alright.

Thanks all of you guys for your help and suggestions, appreciated it all.  I have the same problem as you did. Computer lock- up with 0xc01a001d flickering on the screen after loading loading WINDOWS Vista SP1 as recommended by Microsoft.  I did not see a  cure posted for it yet.  What did you have to do to get your computer running again?   -- Thanks- Litch