@mseliga: Java and Javascript are two very different things. The TinyMCE problem does seem to be Javascript related.
It has plagued our users for months on WordPress 2.6 – 2.6.3 (haven’t got round to 2.6.5 yet and haven’t tried the 2.7 beta).
Our workaround is to switch to the default theme, go to the editor, then change back to our working theme and go back to the editor, which then usually loads OK. The problem keeps recurring. Maybe it’s something in our edited theme?