got issue resolved:
'GeoLocation' doesn't go well with 'My Custom Widgets'.
After installing of 'GeoLocation' our SQL database in regards of 'My Custom Widgets' got corrupted.
Disabled 'My Custom Widgets'
Dropped SQL database
Import of backup SQL database
Enabled 'My Custom Widgets'
*LAST custom widget got deleted (was part of the backup, but gets corrupted after restoring)
we are not sure, if this corruption could be part of some 'code- residue' of 'GeoLocation' or be tainted 'My Custom Widgets' code ...
Luckily we run a backup of our database every night =)
Advice: RUN a backup of your database BEFORE installing 'GeoLocation'
Hope it helps ..