Zone Alarm Internet Security - anti spayware scans

I wonder if anyone is having the same problems that I am when trying to run anti spyware scan?

I have Zone Alarm Internet Security installed and regularly update the definitions profiles for most up to date protection. Recently the antispyware scan has got about a third way complete and just stops at one specific file. Thinking there was some software conflict I reinstalled then ran a scan again - same problem. I then installed AdAware 2008 (free) and the program scan has done pretty much the same thing (though not the same file that ZA gets stuck at).

Any suggestions? I am suspecting some illicict software has installed on the PC which prevents the software finishing a scan.

Regards