Check with Alesis to see if there's an up-dated driver. It's also possible that there are different drivers for XP, VISTA, 7, etc. Make sure you're on the right one.

Which XP service pack are you on? SP3 has been known to cause problems with all sorts of programs. Power Tracks should run happily on SP2 if you can roll back.

Finally, as rharv said, try running MME drivers to see if the problem is still there. Then, at least, we know what we're dealing with.

ROG.