I have a 7400 Version 4.60b and LPv2.00
I had an older Vmail svmi20e in the system and wanted to add email gateway licenses. Upgraded to 5.4.1 and the channels were going Inactive after a couple of hours. A reboot of the card would not get it going again, even though I could log in via serial and see all the menu's etc. A power cycle of the system would solve it temporarily.
I replaced the hard drive on the card and now the system is freezing over night (similar to when the fan tray is faulty)
I can log in via DM and there are no alarms but there is no incoming or outgoing service on PRI or SIP trunks. A system reboot resolves the issue again for a while.
Any idea's?

Definitely sounds like a fan issue, but that would appear in the logs.

Might be worth a default and reupload (4.60b is now 2 versions old so maybe upgrade to 4.75 it has more sip info the logs)h

Is there any part of the software that checks the customer database and might cause the system to freeze if its corrupt. I have turned off Daily Save in 815 and I have also disabled the Auto update of time from the ISDN

I set the system up using Virtual digital ports so that they could re-assign customers new DDI's and numbers. When I make a change on a Digital set key I get warning messages about port mismatch's.

I would backup the system via dm, wipe the db on the sd card, and the system and then upload the db.
Sounds like corruption of some sort, I've found set relocating a lot can do this.