Linked Excel backend

[JimboSHU]

I currently have tables in an access database that are linked Excel spreadsheets as the backend. For some odd reason after using the db a couple times some of the values in records are replaced with #Num! When first linked the values appear fine. They haven't been changed at all so I have no idea what could be causing something like this to occur. Any suggestions?

Thanks for your help in advance.

 

[JimboSHU]

I've also discovered that the only time the #Num! disappears and the values are actually filled in is when I have the Excel file containing the data open. Obviously, that's a problem and doesn't really make much sense. It's only certain values for some reason and it's not as if they were calculated, they were just typed in. Please any advice on eliminating this problem.