Did you only wipe out the settings in HKEY_CURRENT_USER or did you also wipe them out in HKEY_LOCAL_MACHINE? It sounds like you likely wiped them out in HKEY_LOCAL_MACHINE which you should never do because that is where the default settings come from for users, and hence why things will be incorrect in the UI. If you did that, you can try a repair install to see if it fixes it but it may not and you may need a full reinstall to fix it.
I hope this helps,
I indeed did do some selective cleaning in the registry (again after backups) as this is a rather old workstation and there were references up till SW2012 and I must have removed something that did damage. Restored this part of the registry and the strange things have disappeared. My wrong.
Thanks for the help!