If it is turned off already, my next guess would be that youve got a your cookies set to delete too often or youve got a broken cookie for Intuit in there somewhere so its not recognizing you.

Id do a complete dump of your temporary internet files as well as cookies in all browsers and make sure you dont have cookies set to delete on a regular basis (could an anti virus be doing this automatically?), then restart the computer, start up ProSeries again and log in.    Close out the program and start it up again and see if it still does it.....if it does, then yes, Id call support.