As I noted in the previous post, I’ve been tearing my hair out for nearly two weeks now trying to debug a problem with the WordPress 2.2 upgrade that caused many administrative tasks to fail with an error that tells me “You don’t have permission to do that.”
I found lots of other people (here and here and here, for example) having similar problems, and none of the fixes/workarounds they suggested had any effect.
This morning I stumbled upon the cause and the solution. The cause is a snippet of script code that I used in the sidebar for this site, allowing a third-party ad network (Text Link Ads) to serve up ads. When that code was included in the sidebar, the error occurred. When I removed it, the errors went away. As it turns out, the Text Link Ads people have some alternatives to offer, one of which is a WordPress plugin with matching theme widget. When I switched to that option instead, the error messages vanished.
So, if you’re using WordPress 2.2+ and you’re experiencing the “You don’t have permission to do that” error, look for any third-party script code in your template. It could well be the culprit.
We now return to normal posting. Thank goodness.
Ed Bott (@ wordpress.com) 
I had a problem with WP 2.2 recently but it wasn’t with WP itself but like you a 3rd party plugin-in. The other thing is as well that it didn’t affect the running of WP but rather posting to it using the newest release of Windows Live Writer.
It was driving me nut but luckky one of the WLW read my comment on another blog about the problem and contacted immediately. With his help we traced it down to the Bad Behavior plug-in
I wrote about the experience here http://www.winextra.com/2007/05/31/a-full-plate-type-of-day-and-a-big-hat-tip/ incase your readers might be experiencing similar issues.
Terrific! Glad it’s fixed.
Thanks Steven – I’ve been considering using Bad Behavior – good to know.