I seem to be getting a lot of people looking for the solution to the dreaded "1603" error while trying to [re]install MSN Messenger. You could try the solutions suggested in this forum, but I tried them all and I still got the error. YMMV

So I installed Trillian this morning to use in the mean time. After screwing around with MSN's horrid stupid passport system [I seem to have lost the password to my last account and you are pretty well f*cked when this happens] I got everything set up and it seems to be working fine. I'm fungii871 on MSN. I'm also fungii4705 but the bastards don't seem to believe me. I also have another fungii address and something like kajsd;lfkjdsla;ajf when I got really pissed off and frustrated. Trillian might get shut out of their network on October 15 so this might only be a temporary solution. The free, basic Trillian does not currently work on the Yahoo system, but they are testing a patch with their full-price version. Trillian also connects to the AIM and ICQ systems.

Trillian looks much nicer with this skin.

My IM nicks:
MSN - fungii871
AIM - Parkhurstcourier
ICQ - 151807490