A family of Microsoft relational database management systems designed for ease of use.
Why don't you have the mdb? If all you have is an mde, you are stuck.
I can't explain why this is happening all of a sudden and only to you not others. The only way to do that is to see the code that is causing the errors and we would need the mdb for that.
Based on what you have told us, I'm reasonably sure that one of the problems here is the fact that this is not a split database,
You said something about tables may have been unlinked. But the only way that would be the case is with a split database.