That "
Trend Micro Internet Security Pro 2008" have you paid for it already?
It's just that it uses a lot of system resource (Ram wise) and if you have any issue with your Ram memory whatsoever, installing Trend will certainly make it apparent.
If you haven't purchased it, then I'd recommend un-installing (totally) and trying
AVG Free Ver 8
If you're stuck on Trend (your choice!) then you should test your Ram with
Memtest for 7 Passes. Which you probably should do anyway.
I'd like to know your decision, either way.