When you have an original CD and redownloaded your patches to eliminate these crc errors it might be a problem with the RAM or Hard Disk Drive?
When you have a fresh HDD, you can try to format it with the manufactorers tool (e.g. maxtor maxblast, seagate seatools,...). Or just check for wrong sectors within windows.
For The RAM:
Just download a small Linux and make a memory check.
You can find a webinstaller of openSUSE here:
http://download.opensuse.org/distrib...0-NET-i386.iso
Get it, burn it, boot from it, and take the menu "memory check" or something like this.
If you encounter some memoryfaults try to make the RAM slower: switch down FSB and the CAS-latency and other values. Maybe it will help to reduce your problem.
Maybe this would help.
btw: think it's the wrong forum