you must have just installed the patch into the wrong place. I believe that happened to me before when i accidentaly unpacked the patch ".48" into the TCE directory instead of the ET dir. at least thats what i believe happened from what i remember.
another instance that i remember seeing that meesage is when i try to join a server that deos not allow highping users to play, and when you dont have the specific pk3 files and other mod files.
solution is, reintall ET from scratch.
1. remove everything completely
2. install ET2.50, patch to 2.60
3. install TCE.46 ("/tcetest" folder should be in ET directory - or whereever you installed ET)
4. patch TCE.48 (extract the files into the ET directory, not
the "/tcetest" folder)
hope that helps