WordPress MU

I'm in the process of setting up a MU platform. On the Write Post page of one of our 'community' blogs, which has multiple users, the Rich Text editor buttons vanish for certain users.

It only occurs in this particular blog and only with certain users. These same users will be able to see the Rich Text editor buttons on their own blogs.

So far, it seems to be happening with both FireFox and IE 7 and 6. I haven't heard reports of any Opera or Safari users having issues.

Has anyone else encountered this problem or seen any solutions for it? Thank you so much for your help.

im got same error like you got
from admin if i go to users write post backend the page will show blank also in firefox it make my firefox hangup

Which version of WPMU are you running. Have you added any plugins?

If you have Firebug installed in Firefox does it show any errors?

im running WPMU 1.2.4
im adding several plugins but all of the plugins working fine
no error showed for the plugin