That's easy to tell: I hit join, LFS starts up (with a black screen) and the join procedure starts - normally it would load the track details and stuff, but sometimes it just hits the "server no longer online" thingie.
I tried to figure out which version I got installed, but - can't track it down. Can't find a Firefox Plugin, can't find a seperate installation in my programs dir, nor on my game partition. Can't find any *lfs* file names outside above sources, so - don't ask me WHAT exactly I have installed for joining, but anyways, it seems to be outdated.
/edit: "SPECIAL NOTE: You may need to download and reinstall Join2LFS application again since patch Q, because or some changes to the hostnames and browser incompatibilities, which needed to be addressed. As such a new version of Join2LFS is available now via the earlier link."
- Maybe I should just follow the bold printed advices.. =)