Encryption key gets corrupted repeatedly

Hi,
Recently our reporting services started to throw this error: report server cannot decrypt the symmetric key. I restored it, and for a while the problem was gone. Then it started to reoccur regularly. The application vendor stated it was a Microsoft problem. .

As a temp fix while I was working this I set up a batch job to restore the key. I went from 24 to 6 down to 1 hour intervals, as the frequency of failures increased. Still getting worse.

At one point the old key failed to restore, so had to delete and save a new one

Any suggestions on where to look for what might be causing this? Google turns up lots of how to restore but not much why it fails

TIA

Yes I could see the error in SRS log file, as well as event view but could not see anything nearby to correlate it across any of the windows event logs. I was hoping someone had expreienced this and could point to something more specifc to check out, before spending a lot of time way down in the weeds.

Periodic refresh of the key is working well enough to keep the users happy, but that's not really a solution just a band-aid.

Thx - will check that. Odd that its been running fine for close to a year with the same setup. AFAIK the accounts haven't changed. Only changes have been win updates

Our test lab doesn't produce the problem. And I can't control it specifically. It just occurs after so manyreports. Most of the reporting is ad hoc, so don't have a job stream to replicate. And the test instance does not get as much usage. Is there a reporting stress tool out there?

But the test instance has not been refreshed in a while. I'll have to see if the prod instance will cause the problem if I restore it to test. I supose that I would have to restore the report server db as well as the main app's db....