It seems there are some issues with late new installs of WordPress. Namely 2.6.2 and 2.6.3. It seems functions are declared twice, resulting in the plugin not activating and tags not working. Or the plugin not activating at all.

As found on my forum:
here here and here and here also

Obviously i’ve done some research as to what is going wrong. And to be honest, i have no idea.
I have multiple servers in different hosting companies and my own localhost server to test stuff on and all work just fine. Also there is ofcourse my own website (this one). And also here it works fine. That doesn’t necessarily mean everything is alright, but it does mean i cannot reproduce the errors reported and thus cannot fix it. However, and i work in support a lot, i know how my software works, i know how wordpress works so logic tells me people are doing stuff wrong… Not to put the blame on you but that’s just what the situation tells me. On the other hand i doubt all of the sudden people are making mistakes like this and frankly what can go wrong on clicking activate for a plugin. Not much i think. So i have no clue, yet.
I’ve tried several installations on NEW wordpress setups and am working on WP2.7 on my local server to test plugins and make them work with it. Most things work as expected. Everything seems to work as it should on WordPress 2.6.x.

Any information is welcome. Direct it to the forum please so we can all benefit from offered tips, solutions and all that.