Re: "Register as a new user" does not excecute - config error? or bug in v.1.9.8.3 ?
For one of the hosters I terminated trouble shooting with success. Like expected, the files .htaccess and php.ini required to be fine-tuned. (For shared hosting, hence the second php.ini within the customer director tree.) - Permissions required also to be changed for some hosters.
The mentioned files are now looking a bit complicated... PHP configuration problems.... When optimisation is terminated, I will try to add experience and sample files to the help documentation of TikiWiki.
Now selected for permanent use : Tikiwiki Typo3 - both in quality far above average, both complementary. - I hope to be able to supply in a while my thanks for Tikiwiki by own contributions. Planned to develop soon: PayPal feature, extended "friends" features, attractive skin elements, multi-language concepts.