First off, having multiple users sharing a single Front End, sitting on a network drive, is the sure way to repeated episodes of corruption, speed and timing problems, and all manner of strange, odd and curious behavior, including the problem you're having, now! Multiple users simply have to work off of their own copy of the Front End!
Being in forced retirement, I spend 6-8 hours a day here and on other Access forums/newsgroups, and over the past seven years have seen dozens and dozens of reports of the type of set up you’re using causing these kinds of problems as well as massive data lose! The really insidious thing is that it can work for extended periods of time (as is your case) before the troubles begin! But once it does, they become chronic, recurring over and over and over again! You simply have to give each user a copy of the Front End on their PCs.
Secondly, Compact on Close is possibly one of the absolute worse features Microsoft ever added to Access! Ironically, C&R is a recognized cause of Corruption and should never be done without first backing up your file! In addition to this, in a well-designed Access database, there is simply no reason to do a Compact each time the app is closed.
Linq ;0)>