Help please
1.   When the machine is switched it GOES on to start Windows but then it just displays a black screen and the cursor and nothing else! I can start Windows in Safe Mode and all seems OK.
2.   What I have tried before the above occurred is to uninstall Comodo Free Firewall but there is no uninstall button in Control Panel > ADD/Remove Programs! Comodo Firewall is now corrupted and cannot reinstall as it says it is already installed
3.   I have run Malwarebytes which only found 3 PUP which were quarantined.
4.   I have run Vipre Rescue, which found and cleaned one Trojan “Win32.Generic!BT”, remnants of Babylon and Conduit tool bar remnants.
Any ideas on how to uninstall Comodo Free Firewall?
I’m puzzled why when Windows XP runs in normal mode it only displays a black screen and cursor but in Safe mode I can see the desktop?   
When booted to safe mode check in Device Manager...any Yellow !!'s ? ?Boot to safe mode. Open msconfig and on the General tab choose "selective startup" (uncheck all three items) and reboot. Does the problem still occur? If not, start adding items back to msconfig one or two at a time, rebooting after each change, until the problem REAPPEARS and you'll have identified the offending process. This is clearly a time consuming procedure, but it is the best way to determine if some process loading with the system is the cause of your problem.

After you've isolated the cause, do not use msconfig to permanently disable the process. Instead, if it is a SERVICE go to START - RUN and type: services.msc (then press enter) and disable the service OR, if it a program, you can download & run a simple app such as Mike Lin's Startup Control Panel (http://www.majorgeeks.com/files/details/startup_cpl.html) to enable, disable, or otherwise manage startup programs.Thanks guys for your help.
Patio, there are no exclamation marks in Device Manager.
Allan, I will try your suggestion once Microsoft SECURITY Scanner has done its work, which I am RUNNING in Safe Mode, and post the result of your suggestion later.
Allan, I have run XP in Safe Mode "selective startup" (unchecked all items) and rebooted but the problem still occurs  Well, the fact that you can boot to safe mode and not to regular mode would indicate a faulty driver or process, but if a selective startup (which disables all 3rd party drivers & processes) doesn't work the only other thing I can think of is a repair install. Perhaps someone else will have another thought, but if you want to run a repair install here are the instructions:

http://pcsupport.about.com/od/operatingsystems/ss/instxprepair1.htmThanks Allan, I am now running chkdsk /f to see if that helps if not I will run a repair install. Thanks again for your input.Chkdsk did not help so next is to backup the personal data and try a repair install.  For future reference, if you run checkdisk the best method is chkdsk /rThanks Allan, I think I will have to resort to do a Windows xp repair as things have now got worse, I can't even start in Safe Mode anymore.  In that case it could be something more (hd, ram, malware, etc). But go ahead and try the repair.