—-
EDIT:
My webspace provider solved this, it was a problem with a php module on my server. Sorry for bothering & thanks to everyone who gave it a thought!
—-

In advance:
I’m sorry if this problem was posted / solved earlier, I searched the forums, I couldn’t find anything that helped.

I’m having the following problem:

When customizing the template for the member profile update form, hitting the “update” button causes at first a long period of waiting. Afterwards, I get the message that the template has been updated, but when looking at it again, it cuts off after roughly half the entered text.

I’ve customized that template before without trouble, but it just won#t work anymore and I can’t figure out why.

This one simple action created a 3185 lines long error-log on my webserver. I’ll spare you reading the whole thing; the core phrase that keeps repeating is:
>>
PHP Warning:  Function registration failed - duplicate name
<<

Can anyone help me make some sense of that?