A family of Microsoft relational database management systems designed for ease of use.
This fixed it for me...
I just had this issue today. Windows 7 client running MS Access 2010 trying to access a shared database that is stored in a network folder that is located on a 2k3 sp2 server on our domain.
I knew it had nothing to do with the network as I had just added the network folder to the client machine and could see the files inside the folder. I could also RDC to the server from the client, and had internet access on the client. This same client computer was on our domain and other users were able to log onto it and had no problems accessing the database, so it was user specific as well.
The fix (I did) to get it to work was in perfect MS form, I right clicked on the file > open with > MS Word... and told it to always open with that program. I then unsuccessfully opened the database with MS Word and proceeded to close Word. I then right clicked on the file again > open with > MS Access... and told it to always open with that program. It opened normally.
Another (side) tip: When I right clicked and selected 'open with', there was nothing in the list besides MS Access. I 'browsed' to ...\program files\MS Office\blah-blah-blah until I found something that was an application I could select (I don't recall the exact name of it). The list then came up with several MS applications for me to chose from.
Hope that helps!