Outlook clients failing to connect to Exchange this morning.

Anyone else have an issue this morning where all Exchange clients failed to connect to the server? We were receiving emails fine until about 6:30am EST and then nothing. Outlook 2003/2007 couldn't connect and if we tried to connect via OWA, it would let us login, but nothing after that. We also could see inbound email queuing up in the SMTP queue.
We haven't touched the Exchange server in weeks (no changes made) so we were really stumped on what the problem was. We ran check disk on the hard disks and the information store, but everything came up fine. No errors in the event log either.
3.5hrs later we decided as a last chance effort we would try uninstalling ESET Mail Security Version: 4.2.10019.0 and as soon as the uninstall finished.....everyone started connecting again fine.
Anyone else see this issue this morning? Bad virus definition?

 

Sounds like our issue:
https://www.wilderssecurity.com/showthread.php?t=278935

Check C:\WINDOWS\TEMP\ are there a load of NODxxxx.tmp files there? Delete or move them elsewhere, then start (or reinstall ESMX).

Waiting on ESET to fix it, it seems to keep generating these files and not removing them afterwards... eventually there's so many it impacts performance.