Jumping Cursor

When I'm typing, the cursor jumps to another location in that message and enters the next characters in a different place, which I have to delete, then return to the last point of entry. Sometimes it deletes what I just typed (just did it then). The Apple Store genius said it's because I have some old PowerMac software running in background, but I haven't been able to determine whether some of those can be deleted without ruining the function of an application (like Quicken Scheduler, for example).
I've just completed a backup to 4 DVD's, and I'm going to re-install, but that will be a step back, since I've upgraded to 10.4.10 already. Suggestions, please.

Answering my own question, after help from son-in-law...! If you're using a mouse (I have Mighty Mouse attached through Bluetooth) go to System Preferences, unselect all Trackpad Gestures, and then select "Ignore trackpad when mouse is present." That seems to have tamed my kangaroo cursor.

Thanks for posting the solution to this problem, BillMatt! Glad your problem got solved.