occasional "The connection cannot be used to perform this operation. It is either closed or inv

Hi!

I have a website working on connection to MDB, and the strangest thing
happens:
The site could work for hours, and then for half of hour I can't access it
because "The connection cannot be used to perform this operation. It is
either closed or invalid in this context".
It looks like it suddenly can't connect to the mdb. It also happens a lot if
I have just replaced one of the main ASPs.

Anybody has any ideas how to fix this?
Thanks!