Virus Attack and Registry Corruption

A long time ago I may have got a boot sector virus and other evil things. McAfee is quite worthless (ok, although not completely worthless). It simply isn't adequate.

So I went to a list of free anti-virus software to see if anything that is free and effective.

I tried one of the anti-virus product AVAST. After I installed it, it whacked my IE.
I can't open IE, it says there are permission issue. Fine! I don't need IE. Firefox works for me. Then later on I *HAVE TO* use IE for a site that I must go to, ok, I'll try to fix it by installing new IE8. Nope, can't. Same permission issue. Then I clicked on the help html for IE8. ooh it tells me to clean my registry with a command. Ok I obey. I *trust* Microsoft. So Start->Run and paste in the command. It says it is cleaning up the registry... Then it says there is an error and must restart. Ok, fine, restart.

Then BOOM. Can't start Windows anymore. BLACK screen of death, just the mouse pointer can move. Safe mode you say?, BLUE screen of death with the error below:

*** STOP: 0x0000007B (0XF7C9B524,0XC0000034,0X00000000,0X00000000)

Safe Mode with previous working setting you say? BOOM. BLACK screen of death.

The theoretical solution of course is follow more crap such as
http://support.microsoft.com/?id=307545

How can I trust it? I am NOT going to follow! What will I do to the crippled machine?

I will buy a hard disk enclosure, back up the files I need on another computer, and do a clean new install on the crippled one! It is good that the file system isn't broken, just the windows registry.

Lessons Learned
1. Back up often, especially when you suspect you have virus.
2. Save your install CDs
3. Use something better than McAfee