I recently found out that RealTracks is a Background Service.
Try this:
*Change Processor Scheduling to 'Background Services'
Control Panel ->System -> Advanced -> Performance Settings -> Advanced -> and set Processor Scheduling to "Background Services".
Might help, I don't know as I can't seem to duplicate this problem here at this end, but my Background Services have been set to use them as priority for a long time already. It will also help with ASIO drivers, which are a background service as well.
--Mac