I have a large spreadsheet that caculates a loan in which negative cashflows
are added back to the loan. This is necessarily circular. The spreadsheet
works fine usually, but sometimes the circular itteration quits working and I
get #Value errors. If I remove and re-type the cells that have the circular
reference, all is well and the cells caculate correctly.

This spreadsheet has several hundred circular references to resolve plus 2
or three tables based on those circular references. Is the number of
circular references the problem? Is there a work around?