Window Vista - system won't start up?!

[KarumA]

Wanted to respond yesterday, my internet flunked for a near 24 hours bwah...
Most likely something in the registry is failing/broken/missing
You can use the CD as a boot cd and replace/repair the registry with either the standard one fromt he CD or import a backup usually made with any registry clean program.

[amade0]

thanks everyone for the help, I will try these suggestions tomorrow - if not, it looks like its off to the repair again

[ManyVoices]

Have you solved the problem yet? I agree with trying the roll back to "last known configuration" in safe mode. Do you get the prompt in the bottom corner of your screen for boot options (F8)? You say you had a virus before? how did they clean it? Was the shop a friend or an actual shop? If it was a shop and you just got it back they may not charge you as much to look at it again. There so many variables that can cause this it's hard to dx on here.
As for CD's with new computers. That depends on the brand you buy if you get them or not. My laptop came with them but I had to make my own for my tower (two different brands). When you get it fixed ask how to make a backup disk in case it happens again.