I recently got a new HD, as mine was toast. I reinstalled Vista and the COMPUTER was running fine until I had to shut it down or put it to sleep (properly). It would give me the "windows was improperly shut down" error as well as a few system and registry errors until finally loading.

After a few days though, the repair option on my Vista DVD couldn't FIX the problems, and I couldn't load the OS at all due to a "corrupt registry." I clean installed and right off the bat the computer was slow and LAGGING, and I started getting more registry errors... now it's back to unuseable.

Why didn't the clean install fix anything? Is it even worth trying again?
I have antivirus programs (the first thing I did) and registry cleaners and I did a C DRIVE scan.. they all found and fixed a bunch of problems... but still the computer just kept spiralling downwards. I don't know what to do next. Any advice would be greatly appreciated.

Thanks.1) Registry cleaners CAUSE problems, they do not fix them. NEVER use a registry cleaner
2) Exactly how did you do the clean install (step by step)?
3) You said you have "antivirus programs" - how many?