Serious help needed CIS has wrecked my PC after update today

Hi all,
My PC is an AMD Athlon 2400+ with 1GB of RAM. OS is Windows XP Home Edition SP3 and up to date through Windows Update. I am using the l;atest version of CIS 3.8. Ialso have Comodo BoClean and SpywareBalster set as real time protection. I use Superantispyware and Malwarebytes as on demand scanners. I last scanned with them yesterday when my machine was declared clean with not even a tracking cookie found. I did a virus scan with CIS AV two days ago also came up clean. I use Mozilla Firefox with Adblock+ and Noscripts as addons and keep all of my programs up to date on a weekly basis.
This morning shortly after signing into my PC I got a CIS pop-up saying updates were available for CIS. I did not install them at that time but a half hour later when I had time I went to Misc>Updates and received a popup saying updates were available. I clicked OK and the updates downloaded and installed. As soon as I clicked the Finish button I noticed that the CIS icon on my task bar disappeared. I wish now I had tried to open it again from the All Programs list but instead went for a reboot.
On reboot my PC crashed just prior to opening Windows and the next screen I got was the Start Normally, Last known good Config, Safe mode, Safe mode with networking , Safe mode with command prompt. I have tried them all several times and the PC crashes everytime. I cannot get into my PC at all.
After around an hour I decided to try and reformat my PC but although I can get into BIOS when I put the Windows XP Home Edition disc into the drive and shut down the PC instead of opening in the Windows Restore page I get the same screen with the Start Normally, Safe Mode etc. I do not know enough about the BIOS functions to try anything else and do not know how to proceed.
Can anyone tell me if there is some sort of backdoor to my PC through the BIOS in which I can get in and uninstall Comodo in order to get my PC working again.
Any help here would be greatly greatly appreciated.

Does the XP Home edition have a recovery option if you boot from CD ?

Go for the recovery console, you should be able to “connect” to your system and rename a few files related to CIS, that should disable it enough to get started, all though i doubt if it’s caused by CIS if safe-mode is not working either, it looks like something “else” if you wait does it turn in to a BSOD ?

\program files\comodo\comodo internet security\cmdagent.exe
\windows\system32\guard32.dll or guard64.dll if you run x64 bit.

Hi Bluesjunior I had the same experience when using early CIS 3.8 version. my Vista x64 would crash and I was unale to get my Vista x64 running in normal mode.

I had to reinstall everything though. My suggestion is to use the most current version of CIS. That solved my recurring crashes(I reinstalled my OS 3 times). Furthermore I noticed that even after a mere hour of clean reinstallation with all the security software installed and running such as Avira, CIS, Spywareblaster, etc in a mere one hour I found vulnerabilities when I ran the COMODO leaktest.
Until this day I do not know for sure what caused my PC to crash all the time. But I noticed that my PC crashed as soon as I updated the COMODO AV too.

I ended up with installing only the most needed security software and dumped the rest as I suspect them as the cause of creating those security vulnerabilities.

Or it could that my PC was hacked from outside. I’m an online dissident of a country.

In my case it was a black screen of death…safe mode worked just fine though

I have just got my PC working again properly after reformatting my hard drive and reinstalling all my programs etc. I cannot see how it was anything other than the update that caused it to crash my PC and lock up. I had only finished scanning with SAS and the CIS AV a few hours before it happened and both of them came up 100% clean. I didn’t know enough about PCs to try the XP installation CD ROM in recovery mode and could not get on line to seek assistance. The above post was made from the nearest library which is about 10 miles from my home and you only get one hours time on a PC.
Anyway look on the bright side I have learned to reformat my PC and a whole lot of other PC techie stuff the last two days which I couldn’t do before. I lost all my files etc but I do have back ups of most of them.
I think it would be a very good idea though if we could come here and see if a CIS update has just been released at that time in much the same way as we can with the AV updates. We have no way really of knowing whether an update for the CIS is a genuine Comodo product or some kind of malware.

We had the exact same kind of experience. I had to reinstalled my OS more than 5 times.
COMODO should take this post very seriously.
Use the newest version of COMODO CIS bluesjunior. I’musing that and having no problem at all, at least it’s okay up to now.