As you are running MultiCurrency, the 'Clearing Posting Journal' (via period ends) can be found under the Maintenance menu. This is separate from those 3 reports mentioned by Wayne.

The fifth possible posting journal is for Check Reconciliation, and this can be found at the end of the Payments menu.

Should you not be able to run Year End even after printing and purging all the reports, the problem likely is that the data file is not getting cleared after purged when it should. The easy solution is to edit the Company Profile in AP and on the 'System/Report Options' tab, look for the option to 'Allow post journal purge' and disable it. Doing this tells the Year End process to delete all posting journal data files. So make sure you have printouts of everything you need before doing all of this.