Task Scheduled Render - Choke Holds Computer

Pretty much just like the title says, if I use the Task Scheduler to run a batch of PV360 image renders, it slows the rest of my computer down so badly that it becomes completely un-useable (5-10 seconds of lag, extremely poor mouse response, programs can't open, etc.).  In case you're wondering why this matters - I'd like to be able to catch up on emails and research while the images render in the background, and not have to stop-start every few minutes.

This happens regardless if SolidWorks is open (without any files open) or not.  The batch was 5 images, 1280x720 size, 5 parts max, maybe a point light, and no fancy option (like direct caustics).  The render setting was set to "Better". 

Anyone have any idea what's going on?  If it helps, I'm running a Lenovo W510, Quadro FX 880M (with the latest approved drivers), 6GB of RAM, on Windows 7 Pro SP1 64bit, with no other programs open.

SolidworksTask Scheduler