I hadn't changed these from their default and havn't read much into the schedule issues others were having yet.  I guess I'll have to trust the search more. :)

I did turn off Ajax based on a suggestion somewhere and the crashes seemed to go away, but the Application log is still showing the errors.

If you are referring to memory recycling, it isn't set.

I was planning on googling some on performance settings for DNN at a later date.  I've tested these before and was not encouraged enough to change the default settings in a fairly dynamic environment (lots of users updating their own pages/sub portals). So I've left the defaults--cache to disk and moderate.  Are you referring to a specific setting here?