I have over 25 Octel OV250 & OV350 systems running on the 87 date with no issues after cleaning up odd things like an old broadcast message that was never deleted in the system manager mailbox. Any issue from the date would show up immediately or at latest the next day, not days out. The system appears to be rebooting during peak hours. The Abnormal System shutdown type 200 sub code 0C would be caused by a Major System Error. This could be caused by hardware, which it appears you have changed all cards, Drive(s)or a cabinet issue.
A file system error is generally caused by a read/write issue and should not cause a reboot.
The visual messenger pulls the date from the application, not the Octel. That is why they are seeing the correct date. I also have one very large OV350 running visual messenger and they did not have any issues with the date change.The thing visual messenger causes is the amount of connections to each mailbox, like every second, to keep the application up to date with the users mailboxes. That is a real load on the Octel.
It is odd that the issue started after you had a power outage but you stated that the Octel never lost power, BUT could it have had a power surge?
At this time I would be looking at drives or a back-plane issue. Make sure all voltages on the back-plane look good and no burned traces.
** Be careful on changing the year up to 2009, this could purge all messages when the system runs the midnight routine for all old messages.