Welcome to MR, slickhead. I seem to remember seeing something about XP prof and SP3 but can't find it exactly..
I don't have any experience nor have I had any problems so far as I am still using v2.5. Just in case you haven't seen the below threads.. here are the links....
https://www.mobileread.com/forums/showthread.php?t=55041
https://www.mobileread.com/forums/showthread.php?t=56428
I hope you get it solved. If you do, please post back here so we can learn also. Thank you.