I had a call from one of my users today to say his database was just closing down as he clicked a button.
I got his front and back end files and ran them on a PC with Office 2010, they worked fine, but his Office 365 has been updated today and he has the problem on all his PC's.
I tried the front/backend files on two PC's I have that are running Office 365 and they too have the same issue.
It seems like Microsoft has broken things.
Is anyone else having issues after today's update?
UPDATE: This mentions that the recent Office 365 update fixes problems in Excel, Outlook and Word, what it does not mention is that it broke Access!
I managed to program around the main issue I was having, however I have just seen messages to say Microsoft have fixed it, I just tried the original database and it seems to be working fine. Thanks to everyone who posted their experiences here, it was very helpful.