MD5 tool mismatch scan the whole cvars (written in the pbcfg server) contained in your quake files. Some of your packs are not default and that's why you got kicked by pb.

If you never use cheat, best way is to reinstall excessiveplus and if it doesn't work reinstall the whole quake 3 and this time don't edit any pack.

If you executed cheats then go away from here

in excessiveplus directory you have a file

z6_low_explosions.pk3

delete it.

@Angleos dont worry, you do not have to reinstall all Q3 and e+ just look in your Baseq3 and look for the file z6_Low_explosions_pk3 and aslo Q3 chat_bubble and also z6(I think)_new_rail.pk and also rbx_circle_plasma.
If they are not in baseq3 do a search in E+ folder for these files and delete them all.
These files can be downloaded from servers in maps or pk files, so best thing to do is disable autodownload in q3 menu. If there is a map you dont have do a search on internet for the directory of q3 maps and get it that way.
I was kicked from 2sweet freeze for low explosions and didnt even know it was in my directory, so atuodl is definately OFF.
I think these files have recently been added by the guys at evenbalance(PB Guys) because loads of players have been recently kicked for them.

Regards

YES. On some servers are shits. If you want have clear q3 game, disable auto dowlnoading in menu of game (game options(?)) Iam recommending you download from servers only maps