CCleaner won't load

I am running the latest version of CCleaner on my WinXP system. I have been successfully and happily using CCleaner for years but a problem has arisen. When I run CCleaner, nothing happens. It is running in Task Manager, but I cannot access it, switch to it, etc. I have uninstalled it both normally and with help from Revo uninstaller, re-downloaded and re-installed multiple times to no avail.

My system: P4 3.0, 2gb RAM, 500 GB (RAID 0), WinXP home. Using AVG8 Pro antivirus/antimalware and Comodo Pro firewall 3 with Defense+ turned OFF. No significant changes were made to the system prior to this problem arising. Any ideas?

Thanks!

When you say nothing happens, do you mean it freezes? Can you see it on the screen?

Will it run in safe mode?

Have you tried the slim version from here?

http://www.CCleaner.com/download/builds