After installing ZIS 7.1 15-day trial for Windows Vista Business, my desktop slows to less than a crawl every time I open a web browser or attempt to update virus definitions with the only remedy being a reboot. I tried to see what was causing it in Task Manager, but it gave me some security dialog and I couldn't access it -- I suppose ZoneAlarm reduced my privileges. I managed to open a Sysinternals program called Process Explorer and it showed that my entire CPU was being (evenly) used by "DPCs" and "Interrupts". After turning off Program Control and rebooting I was able to open Task Manager, and was surprised to learn that it was Task Manager taking all the CPU; actually the top spot was traded between a few other programs as well, notable the browser and dwm.exe. After uninstalling the problem seems to have vanished, although it appears that at least one of my quarantined malware has reinfected the computer. Does anyone know how this can be fixed or could recommend the second best Internet Security Suite?

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