@ivovic: It wasn’t always like this. Before upgrading to WP2.5.1 I was able to post perfectly well.
You know, I’m using eUKhost as well…
Edit 1: I’ll try this about mod_security in .htaccess and see if that works.
Edit 2: That seems to have worked… if I get hacked I’ll blame them!
Thanks mellojoe. I think that’s only true for IE6 (it seems to work fine for IE4, IE5.5 and IE7), but I’ll have a look at that. And I’ll have a look at that red.