i used to have a similar problem, but it was in GP4.
seeing as GP4 is basically GP3 with better graphics i'll tell u what my problem was.
i recently installed a faulty XP patch which came with there automatic download thingy, n this made PO in GP4 go to 300% odd. also, when i looked at the task manager my CPU usage was 100%.
i had to reinstall windows to fix this problem, as uninstalling the patch made XP not start.
u will probably experience slowdown in all your games if this is the case, and check that ure CPU usage isnt constantly 100%. if it is, then you'll have to look for a fix on the web, or get that XP CD out.
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