As I said in http://www.in-nomine.org/2009/02/22/tinymce-in-wordpress-271-not-working-on-freebsd/ I had problems making TinyMCE work.
After some digging I discovered that the tiny_mce.js file was being oddly truncated and repeated when fetched. Subsequent tests showed that md5 hashes differed every single time with the original file.
During these fetch tests my kernel crashed twice in the network stack. Since my lighttpd configuration uses kqueue and the likes I suspected that perhaps something was not right in lighttpd 1.4.21, which was only released a couple of days ago. So I downgraded to 1.4.20. ‘Lo and behold, the problems disappeared. To be absolutely sure, I recompiled lighttpd 1.4.21 as well. And at first it seemed to work, but then the corruption kicked in again. After talking about it on the #lighttpd channel on FreeNode I found out it was a problem with lighttpd 1.4.21’s handling of sendfile() on FreeBSD.
The fix is now also in the lighttpd port of FreeBSD, so other people should not encounter this problem.