So I figured out what they've been doing...
There are three ppl writing cheques, so their bookkeeper sometimes doesn't see a cheque until it clears the bank, then when she posted the cheque she backdated it to when it was written, if it was a prior period it screws up all the prior bank recs. The problem came b/c we were doing a review engagement (Dec y/e) and the only bank rec that worked was the one from April/05, so I have to work all the way back until it works again! ARGGG... Oh well, almost done.