I finally resolved this problem on my system running Windows Server 2003 with IIS. I installed WordPress v2.2 and ran into the same AJAX error. It ends up that the spell checker config.php file was configured to only use Google’s spell check web service. However it requires the use of SSL which my PHP was not configured for.
Long story short I modified the config.php file and had to hack the TinyPspellshell.class.php file but was able to get everything working (although I had to install a copy of aspell.exe).
I posted details on how I fixed this:
https://www.roth.net/blog/index.php/2007/06/25/wordpress-v22-spell-checking-problem/
I hope this helps someone.
Cheers!
