I was running just fine at Mac OS 10.3.3.
Upgraded to 10.3.5 and voila! no more online Ghost Recon or Raven Shield - I'd crash out of every host. Most amusing, because for the Ghost Recon rooms I was trying to join (Zippo:SOG) - I was the one who had converted all the mods to the Mac side. Most interesting.
So if you are at 10.3.5 and experiencing crashing, there were new drivers installed for Nvidia and ATI.
Some people report no problems with 10.3.5 however.
Best way to resolve, or what I did, rather - was to reinstall Panther by Archive and Install (preserve Network settings, natch) back to 10.3.2 from the original Panther CD then upgrade to 10.3.3 if you like, just stay away from 10.3.5 if you were crashing due to games.
Caveat - the new drivers in 10.3.5 DO NOT prevent you from playing offline that I can see. Which thus smells like a Gameranger issue, but what do i know