Install help needed!

Hi Guys,

Hope you can help? I was running Comodo Firewall with AVG 8 and I decided to upgrade to Comodo AV free.
I un-installed AVG 8 and then ran CCCleaner to get shot of any reg files. I then installed CAV from the install download (add AV only), all seemed fine until I tried to run a virus scan, the system froze after about an hour and wouldn’t do anything.

I un-installed the lot firewall and AV I then removed all the reg files and changed the DEP (as read in the forum). I tried to reinstall and again all look ok until it asked me to re-start, once it powered up Comodo would not open and it ran a Diagnostics and said that it had fixed the issues and that I had to re-start my machine.
Once I did that I now had only the firewall and no AV part. I then tried to just install the AV as before but again once installed looks ok until I try and run a scan and then it freezes again.
Can anyone help please?

Windows Xp SP2
AVG 8 which was removed
Mailware which was also removed before trying to install AV
BoClean which was also removed before trying to install