Yes, I use a custom german language file (The forum is completely integrated with WP i.e. both configurations are loaded).,
I just tried posting links while not using the language file: no change, href still gets stripped.
Deactivating all my plugins doesn’t help either.
Also, for some reason ” does not get unescaped. I get ” all over the place. This I was able to fix with a custom stripslashes-filter. Its strange though that forum software comes with such bugs out of the box…
The href must be stripped when saving a post, as it does not appear in the database tables. Some pre_post filter maybe?
My german forum is located at http://www.sphaerenriss.ch/forum/
Thanks for your help
Eight so far. But the forum is far from complete. 
I would much rather have stuff like “Unread Posts” and a post preview integrated into the bbPress core than having to hunt down each and every piece of functionality my users expect from a forum.
Could it be that the tag you are trying to delete has spaces in it? I get this same error when trying to delete such a tag.
I have the exact same problem. An yes, I already tried deactivating the “Allow Images” plugin. 
