I've been using ZAPro for 2 months already (used Agnitum Outpost before) with WXP and never saw the problem. Check the other launched proggys for a conflict,
or use the latest version or see the settings(although I think it's not them).
It's not a PC problem - I'm pretty sure. My PC is Duron 750 Mhz, 384 MB SDRAM. It should be software.
P.S. Yuk what a lamah advice. Sorry Dad. I'm just trying to help (But who am I to help Dad):o