I removed Momentics but I still could see an item in API levels in Options->BlackBerry->API Levels and Runtimes, so I tried to "remove" it. A Dialog poped up "Uninstalling" the progress bar stopped at 24% and nothing happend after that. I could remove the API levels with "Clean". There are two items under "Runtimes" that cannot be removed due to the described error.
I am trying to reinstall BB NDK and Qt SDK.