Looks like a problem with NPLoader:

[quote:d73a6d5e29]
DevNet: Join succeeded: Bounce
ScriptLog: [NPLoaderv16b] Player Join: Bounce (XXX.XXX.XXX.XXX)
[color=orange:d73a6d5e29]ScriptLog: [NPLoaderv16b] Loading failed for player: Bounce (Reason: Installation of new mods required)[/color:d73a6d5e29][/quote:d73a6d5e29]

NPLoader is used to install the client-side files for our anti-cheat.  We had another guy have problems with NPLoader but for a different reason.  NPLoader 16b seems bugged?  There's not a lot of documentation on NPLoader and the code was stripped.  I'm sure that's to create a roadblock for cheat developers but hopefully it's not going to drive me insane...

Try downloading this and extract the files into your UnrealTournament/System folder:

http://download.dfbgaming.com/ACE_v8g.zip