so it looks like my Nvidia card / driver is no longer supported. is it possible to use and older version of Studio to process the footage I have already shot? the studio I was using two years ago was working well with my graphics card / driver.

Two years ago it was version 2. You can still download it at this page (look at the bottom).
http://ipisoft.com/support/

Version 3 supports only DirectX 11 compatible GPUs. Most of the video cards released since 2010 meet this requirement.

huuuge thanks vmaslov! will version 2 of mocap studio process footage recorded with the most recent version of ipiRecorder?

nope. it does not.

Yes, you're right. V3 records can not be processed with v2.

one of the few times I hate being right. :)