CRC error on installs, downloaded, virtual, disk, or patch

[Krayon]

Hey all. I've recently been having issues with installers.

I'm running XP Home SP3, with the following System specs:

Intel Q9550
6 Gb DDR3 RAM (Memory checks ascertained that these sticks worked, but that might have changed in the last month. It's a Dual Channel system, 2 sticks run with one power scheme and the third with another. They are on separate channels.)
4 T HDD
Nvidia Geforce GTX 285 1 gig
Gigabyte GA-EP45T-DS3R motherboard (latest BIOS installed)

All drivers have been updated as of the last month. The install was done from a clean install last month.

The problems began about 1 week ago. I have not been able to pinpoint any possible causes, or changes in the system that could have done that. It seems spontaneous.

The actual problem is as follows:

I get a CRC error on .cab, or .dat files, or other extractables, during installation from any medium, CD, virtual drive, downloaded .exe, and patch, manual or automatic. Small installations (under 100mb) complete without issue. After that, it's touch and go whether there will be an error. The errors are random and not always the same file at issue each time.

I've tried most conventional methods, reinstall, copy pasting files when possible, deleting offending files, retrying till they work, reg cleans, CCleans, defrag, installing on a separate HDD, installed the latest windows msi, chkdisk etc.

NONE have worked.

This is bad! I can't install or patch ANYTHING! Even 47mb patches don't work!

If anybody can help. I would be grateful!

PS - I know what a CRC error is, and have tried using alternative working CD drives, over a network or external. No go.