I had to remove a former installation of Debugging Tools and MSVC2010 Express. After re-installing them in a different way than the first installation Creator wasn't able to find CDB from Debugging Tools.

First approach was C:\Program Files\Debugging Tools for Windows (x64)
After de-installing I installed them again - but this time via the WinDDK ( http://download.microsoft.com/download/4/A/2/4A25C7D5-EFBE-4182-B6A9-AE6850409A78/GRMWDK_EN_7600_1.ISO ) because I had some trouble with the WinSDK.
After this installation the Debugging Tools where located inside a subfolder of the WinDDK installation (not even named 'Debugging Tools for Windows (x64)').

After removing the config files of creator it couldn't find the Debugging Tools (especially CDB) even though cdb was added to PATH and usable via cmdline.

I had to remove the WinDDK, solve the trouble I had with the WinSDK and install Debugging Tools from WinSDK again to make Creator find the CDB again.