What version of Windows are you using?
Do you have multiple versions of Office installed?
I was using Vista when I first installed A2007 on a PC that also had A2003. After a week, I was ready to toss A2007 out the window because I was getting truly bizarre errors. After days of searching, I discovered the problem. We all know that Microsoft's children don't play well together but in combination with Vista and newer OS', the problem is fatal. When you switch versions, you get the "installing" message as one version attempts to take over the registry from another. The problem with Vista and newer OS' is that because of security, this "takeover" may not be complete so you may end up thinking you are running one version of Access but many of the libraries you are using actually belong to a different version. There were three options offered as solutions.
1. Modify the registry - I don't remember what keys needed to be modified but this didn't work for me because I was distributing an app to the general public and didn't have the ability to modify their registry.
2. Create shortcuts for each application that includes the full path of the Access version you want to run the app and set the shortcut to run as admin. - This works for users because they have a limited number of applications they use and they don't do development.
3. Create a shortcut for each Access version with permission to run as admin. - This is what I chose for myself because it gave me the most flexibility. So, rather than double-clicking on a database, I would choose the Access shortcut for the version I wanted to run and then choose the app.
Beyond this issue which was caused by security permissions, I haven't had any compatibility issues. If it works in an older version, it works in a newer version as long as it compiles. You will run into code that no longer compiles because of changes to VBA but once you get past that, the compatibility is actually remarkable.
