When I enable the Anti-virus On-Access, the system is slow and the Anti-virus is always accessing HDD.

I was going to uninstall ZASS 7 and I've tried one last action.

I went to System32/Zonelabs/avsyst

And I put comptability to scanningprocess.exe to Windows XP Service Pack 2 and since then, it works as it should.

Operating System:Windows Vista Business
Software Version:7.1 (Vista)
Product Name:ZoneAlarm Internet Security Suite