Once you've ensured that you have the most up to date version
0.3z_r2 (
http://vicecitymultiplayer.com/?a=download), it might be worth checking that you've installed VC:MP into the correct area/directory where your GTA: Vice City game has been installed.
While you can make a shortcut of the VC:MP client and place it anywhere, the VC:MP files themsleves need to be in the game folder.
Why not try adding the
Argonath RPG server IP - 149.210.148.192:5192 to your Favourites tab (first one, left of Internet down at the bottom)? That way you can connect to the server direct without having to search it on the full list - which may not always be online.
A problem I've seen going around on 03.z is this:

Hopefully that error is not affecting you.