ATIH 2012 Backup Validation brings computer to its knees

I am running ATIH 2012. Win7, quad-core, 8GB RAM. I can create backups in the background and never even know Acronis is running. But when the Acronis scheduled task for backup validation fires up, it brings my computer to its knees! WHY?!? CPU loading during this peaks at 21%, but the computer is completely unusable. Launching programs takes on the order of minutes, not seconds. It took 3 minutes just to bring up task manager! You would think the backup validation should be lighter than the backup process. Lest you think this is a new problem, I've had this problem with the last two versions of Acronis as well.
-Unhappy customer.