Ok... here goes. This all started after I installed a new fan on my cpu. I then proceeded to test it out and decided while I was at it, I'd upgrade Windows XP. Keep in mind my PC has been up and running since January with no problems. I downloaded service pack 1, using IE, and things started going bad. I got random crashes and programs that worked fine before now began to crash. So I thought, must be Service Pack 1. I wouldn't be the first person to experience problems with it.
I did a reinstall of windows xp using quick format. Updated some junk, but not to SP1. I start having problems downloading .exe files, zip files, .rar files. They all became corrupted. Or, atleast the majority of them did. But no random crashes. Keep in mind that I have tried both Firefox and IE for downloads.
So, I completely reformatted my drive. Not the quick one, the extended 40 minute, check for bad sectors and write zeros one.
Now, I've got Windows XP Pro (no microsoft updates this time) up and running, and again without random crashes. But I still get the damned corrupted downloads.
I've done the following:
1. Made sure only one NIC was installed. There were two being seen in the device manager.
2. Used Seagate's Seatools to check my hard drive. It says there are minor inconsistencies, but that there are no errors and that things should work just fine. I also used Microsoft's checkdisk utility with the /f option to fix stuff. No problems found.
3. I used Ewido to check for malware using a very specific proceedure described here involving safe mode and upgrading ewido. Nothing found except some cookies, which are NOT the problem. However, when restarting the PC one time, ewido told me that some of IT'S FILES HAD BEEN MODIFIED!!! and that I should run the updater again, which I did and proceeded to use ewido again to check for viruses and malware. Afterwards I checked to see if it's files were changed, but they hadn't been that time. I'm thinking this may be caused by a virus or perhaps a bad hard drive... keep reading.
4. I also used avast! to check for viruses and such. Nothing found.
5. My most recent attempt was to install my copy of McAfee Antivirus, purchased in January, which was a bitch to upgrade and get up to date. It took several attempts to upgrade McAfee, as if it's own downloads were being corrupted. I actually had to update it in safemode, which only worked after the second time.
Whatever this is, it is really owning my pc. I'm an IT guy myself and I have no idea what to do next. Any help would be greatly appreciated. There's 500 points in it for someone who actually figures this out.
Thank you all in advance.