Yes this happens once in a while for some reason.  My gut tells me it is when someone opens the company file and on the session date screen changes to the new fiscal year.  A couple of people have mentioned their computers and Sage 50 were running for days or weeks before they transitioned to the new fiscal year.  I just don't have enough evidence and haven't taken the time to test it.

You can't fix this directly if the Data Integrity indicates an imbalance between Debits and Credits in the Data integrity check on the Maintenance menu (always check this after transitioning to a new year).

I have been hired to fix these especially when it goes a couple of years before someone notices it.  In fact two weeks ago I fixed one for an accounting firm for their client.  However, because your issue happened just in the last fiscal year transition, you should be able to call Sage Tech Support and get them to do an internal rebuild over the phone with you.  If you have a support plan, they should do it for you for free.  You will have to be able to log in as sysadmin to accomplish it and make sure you get a good back up of your file before it is done.  Waiting on hold will take longer than the rebuild.

Thank you, Richard.

I will contact Sage Tech Support.

Thank you, Richard.

I will contact Sage Tech Support.