PC sometimes hangs on boot

[razorblade]

Hello there

I've a PC:

Intel Quad Core
Intel MOBO
2 GB RAM
320 GB SATA
Windows Vista Business 32
Office 2007 Basic
AVG 8.5

Sometimes when booting PC hangs, when try to boot in safe mode it stops in CRCDISK. After a few tries it boots normally.

I have already run all kind of disk and memory tests everythig seem to be ok.

I've noticed that someone (probably during PC assembling) has disabled the SMART feature in BIOS, but enabling it won't solve.

Now I have no idea at all.
Any usefull help is welcome.

Razorblade