I have attached the full error message that a test user and I receive randomly while using the grid.  Mostly the issue occurs while grouping/ungrouping columns but for no specific columns/data/etc.  I know the information is relatively sparse but wanted to see if anyone has seen this and could know of a possible cause.  I'll try to put together a sample application and see if I can replicate it, but I doubt I would be able to replicate it outside of this app because it just started occurring around last week.