Severe corruption on attempting to uninstall and crash causing data corruption.

Hello there,
I have been using comodo for quite a few years now, and am largely very happy.
Unfortunately I have run into some serious problems more recently

Background:
system:
Windows XP sp3 (up to date with hotfixes etc.)

Intel Pentium D 930 processor
4GB memory
Asrock 775Twins-HDTV Motherboard

comodo internet security premium 8.2.0.4508

Backup software: Paragon Backup and Recovery Free 2014
Disc Clone software: Easus DiskCopy Home

Initally problems started when I was getting some performace problems on startup. So I decided to reinstall comodo (long waits while comodo initialised). I used Windows uninstaller from Control Panel and ran the Comodo uninstaller.
Restarted windows, most programs I tried were unusable, Word, Firefox had lost all their settings. Looked for deleted items using piriform’s recuva, and found nothing. It looked however that Documents and Settings had become corrupted.

Tried a system restore to a known good point. No better.

Solution: restore a disc image and go back a few days. ( I image my C drive weekly).

I did not attempt the uninstall/reinstall process.
Comodo updated itself and all was (relatively) right with the world.

However, two days ago I had a hard drive problem. One of my SATA data discs was reporting bad blocks. Clearly this had to be replaced. I replaced the drive with another smaller one. I had another old IDE drive which had on it an old clone of my C drive. I mounted this in a USB caddy. I wanted to use this for additional data backup. I removed the partion as of course it would not mount. I reformatted, but windows kept asking me to reboot for the drive to be usable. Windows could see the drive but would not allow me to assign a drive letter. I’ll grant you, this looks like an XP problem.

However, during this process ( as i again attempted a format on the USB drive), a message flashed onto the screen which contained the words: CIS Internet Please reinstall the product. Unfortunately this happened very quickly and disappeared and the machine froze. I attempted to restart in Safe Mode, however the machine just sat there with the “logging on to windows” splash banner flashing. I attempted to restart in safe mode with a command line. Same result.

I attempted a “last known good” restart. The machine booted as far as the logon screen this was then followed by “saving your settings” followed by the logon screen followed by “saving your settings”. Whether the loop was infinite or not I don’t know, but it was clearly a long term loop!

I restarted the machine from another boot drive as linux, and the file system of the C drive did seem to be intact. I don’t have the tools to examine / edit the windows registry from linux as yet. Simplest thing to do was to restore from a backup to a different disc from the corrupted boot disc and make sure that files from the broken operating system were copied ( via linux ). This worked and the system is up again. I still have the original corrupted C disc set aside for forensic examination (for the time being, I could really use it for data backups).

I would very much value any help or suggestions regarding this problem.

Corrupted C Drive: Hitachi CinemaStar 250GB HCP725025GLAT80

Thanks in anticipation, it would be great if anybody has any ideas as to how and why this might have happened.