My customer called and said his PC was unable to boot. It was reporting a "System Disk Error". I told him to bring it by and leave it with me. When I started the computer, there appeared to be no problem booting. It went all the way into Windows XP and ran fine.
Windows XP has all the updates and Service Packs.
I discovered the PC was infected with the "Win32.RBot" Trojan. I used SpyBot and Malwarebytes to eliminate the infection. I then ran multiple Virus scans.
The computer was with me for 2 days. I ran ChkDsk, defragged, and used CCleaner. I cleared the System Restore caches, ran the AntiSpyware scans again, and restarted multiple times. Everything seemed to work fine. I returned the PC.
The customer called me after he got home. He said he tried to start the computer and he was getting a non-system disk error again. When he brought the PC to me again, I could no longer boot into Windows XP and was getting the same error he reported.
He left the computer with me. The hard drive is a Western Digital EIDE drive, model WD400BB. So, I checked the drive with WD Data Lifeguard Diagnostic with a DOS CD. The diagnostic misreported the Model as WD102BB and reported the capacity as 0 GB. But, both the Quick and Extended test reported the test as "Passed".
I don't know what else to do, but tell the customer that I need to install a new hard drive and reinstall windows. He has no backup and no CDs to reinstall the OS and software. As this is an older computer, this will be cost prohibitive.