I've run into this issue for some reason and I've read and tried everything I could find.
First let me say this isn't the easy Tools > Macros > Security = Low message.
Here is what is happening. I've created many access databases over the years and put them on a shared server for other users at our helpdesk. Never had an issue with this before. Because we are on a military base and our servers are located with the bases IT dept...they push security updates, patches, etc without even notifying us. It's very frustrating. Suddenly one day ALL of our databases on this shared server come up with this message:
Open File - Security Warning
Do you want to open this file?
Publisher: Unknown Publisher
Type: Ms Access
Click on Open and it opens fine. That's not a big deal to just click an extra button to get into the database. Here's the kicker...the first person to open it gets that message, but any other users that try to get in after cannot double click it or use their shortcuts. It just does nothing double clicking. The only way for them to get in after someone is already in is to go Programs > MSAccess. Then hit file open and navigate to the database and it will open.
IE 7 was NOT installed, I've tried sandbox = 0, 1, 2, 3 which did not help. These are databases that I created and open up without that warning on my own harddrive, but from the shared server I get the warning. Is there any other workaround for this I may have missed searching around?