Get "snoopdos" from aminet. When its loaded, it will monitor your computer and tell you what files your programs are trying to load. This is an essential amiga tool, because it will easily tell you if you are missing files that another program needs.
I just downloaded jabberwockey off aminet, to see what it was like (MSN on amiga).. It said cannot create MUI application. I ran snoopdos, and tried it again, and it turned out it was missing a texteditor class. I went to aminet and searched for it, installed it, and now jabberwockey starts up fine. Just have to figure out how to use it now.

Aminet address:
http://wuarchive.wustl.edu/pub/aminet/Good luck Gav.
-Edit-
I'm trying to register a new jabber account, but it just says "connecting.." for ages. I've tried registering with three different servers.. jahc00@jabber.org @jabber.net and @amessage.at ... :/ Does it matter that I'm using WinUAE?