Make sure you have the latest service pack installed for AP = 080821. YOu can find out which service pack in installed by looking at Help/About.
Backup your data.
Run data integrity check. If any errors are found run the Rebuild function. Repeat until no errors are found.
Still can't run the Year End then;
Run a period end. If you have auto print posting journals turned on then do not print and clear the report.
Now go to the Print Clearing Posting Journal/ Print this report for the entire range of posting sequence numbers indicated and clear it when prompted.
You should be able to run the Year End now.