That's extremely odd as we absolutely do not use Microsoft Visual C++ (nor any other Microsoft compilers...) to program SpamFilter.

Do you use the antivirus plugin? The DLLs used by the A/V are third party applications that are instead created with Microsoft C++.

Could you zip and email us SpamFilter's activity logfile for the day it crashed, so we can hopefully try to see if there are any pointers as to what may have happened?

From the logs we see that SpamFilter was working without a glitch even with the error dialog box on screen, until 9:52:44, which is when you "OK'd" it. This supports our initial theory that it is not a SpamFilter error (as again we do not use C), but rather an error from another appliction which took "ownership" of a SpamFilter thread, and that shut down SpamFilter when it errored out.

Please note that these are all theories, as in the last 4 years we've *never* seen anything like this...

Going back to the logs, we notice that between 2:10:00 and 2:14:48 your MySQL server was unavailable. Could you please check the MySQL logs to see if there were any failures at that time? A remote possibility is that MySQL shut down the process that owns a connection (SpamFilter...) when it crashed, and this only occurred when you clickeed on the OK button.