Captivate 6.1 fatal error - app terminates & saves work in .cpbackup files

I am working with Captivate 6.1 via a subscription license. The current file was created from scratch at 2048 x 2100 for new iPad retina resolution. While only 2 slides, the file is complicated - most images hidden and grouped and then called as groups via advanced actions.

Today I started getting "A fatal error has occurred and the application is being terminated. Adobe Captivate has tried to save all your work in the respective project folders as ".cpbackup" files. Please restart Adobe Captivate."

I deleted prefs and cleared cache as instructed here: http://forums.adobe.com/thread/1267044. Same. I backed up and started using a file from about 30 minutes before. Same. I backed up 2 hours and started using that file, worked slowly and methodically... eventually same.

Here is what I am noticing:

• Application seems to run slower with delays whenever I touch the x/y location of any item.
• If I mess with groups at all, I am likely to crash the file. Culprits include changing order of objects in the group. Adding additional objects to existing groups. Changing the order of the groups.

Is there any way to recover existing work?

Should I just start over without using any groups? I was using groups to make advanced actions easier to write and edit. Any known issues with groups in Captivate 6.1?

Am I dooming myself with 2048 x 2100? Any known bugs?

Thanks! Appreciate the help!