I have Office 2007 SP2. Yesterday I installed Office 2010 beta (which involved uninstalling Outlook 2007), played with it and
decided to go back to Office 2007. Uninstallation of the beta went ok but OL 2007 didn't start. Eventually I got it to work.
Here are subsequent problems that were coming up and their solutions.
Problem 1: OL07 didn't go past the splash
screen and said it wasn't able to load Emsmdb.dll.
Solution: Apparently OL10 had deleted emsmdb32.dll from system32. There should be a cached copy of it on your hard drive.
Search for emsmdb32 and copy it to system32. If you don't have it, do the same as for mspst32 below.
OL07 says "Cannot open your default e-mail folders. The information store could not be opened".
Solution: This is because OL can't find mspst32.dll. You can copy it to system32 from the local cache. If that solves it,
fine, but it may also cause the next problem.
Problem 3: OL gets past the splash screen, partially draws the UI
(menu and task bar), then crashes.
This is caused by different versions of OL and mspst32.dll that was copied from
the local cache. In my case, outlook.exe was 12.0.6514.5000 and mspst32.dll was 12.0.4518.1014. Office repair, reinstalling
OL, removing & reinstalling Office SP2 don't help because they don't touch this DLL.
Solution: You will need to
get a hotfix or a patch with a suitable version of mspst32 and manually extract it from there.
1) Find a hotfix with the version of mspst32 that would match (or be higher) than the OL version. For the OL version above it
is, for example, KB972363. (Btw, it's not as straightforward as point-and-click ;)
2) Get a tool that extracts the contents of the MSP. For example
3) Go to the .cab file, find the DLL, copy to system32.
Hope this would be helpful to somebody.