I just had this problem today with a client using windows defender! I had upgraded them to 2017 PU3 and it was working fine for over a week until today. It removed PRB so when they went to run payroll tax calculation, they got the error. The error was #12 line 8825 and in the knowledge base, it recommended re-initializing PR9, PRJ, PRK, PRL and/or PR_02. It didn't address removing the PRB. I did everything else and then started going after the Microsoft Windows Updates from the knowledge base as well after the initial steps were taken. After this was done, I noticed the error was referencing PRB so I also reinitialized that and then their IT company started working on the antivirus so unfortunately we don't know which one fixed the issue. Sage engineering said they were going to update the knowledge base to reflect PRB in the list of files to manual reinitialize. I think once the PRB was manually reinitialized, it started working however does anybody have a solution to the windows defender issue?