I have the exact same problem when trying to get into this server.
If i set LANG to English i get:
Error: Assertion failed: retVal>=0 [File:.\UnCanvas.cpp] [Line: 5594] (the same error that op get)
And if i use the Localization file that you (Trolya) provided (LANG:Europe) i get:
Error: StaticMeshActor Lobby01_Classic.StaticMeshActor42: Serial size mismatch: Got 150, Expected 152
I have been browsing the net and found that people in other servers have had similar error and one of the supports of another server advise them to change "UNICODE" in system (control panel>language>location>Administrative>Change the system's regional settings>and choose "Russia". I haven't tried this because i don't know what this change is going to do to my system and if by any chance this change my OS language to Russian I’m screw because i don't know how to read Russian and i wouldn't know how to revert said changes.
I really don't know to do... this is the first time I’ve got this kind of error on any server.
P.S: If you could make a Torrent to download your client a lot of my friends would appreciate it, because they don't have fast internet connection and they hate direct downloads.
Cheers.