This may indicate a corruption of some of the DLLs installed by Studio.
Instead of using the "repair" option, try this:
1. Exit the MapGuide Studio application
2. Use the Window Task Manager to make sure that the DETE.exe process is not running. If it is, kill it.
3. Uninstall MapGuide Studio.
4. Go to the MapGuide Studio installation folder and delete any files and folders that did not get removed by step 3.
5. Reinstall MapGuide Studio.
Bill