md5tool scanned your gamefolder and found cod4bot.exe file, which is cheatfile.
here“s the actual pb ban-message
011 193-33-186-223-28963.log [10.27.2009 17:32:24] ->PBSV: VIOLATION (MD5TOOL) #9002: [KR]OPEJI (slot #12) MD5Tool Mismatch: Cod4Bot.exe (len=204

[f538a935f86891db58d359b487e5d6dc(VALID) 217.88.168.115:28960]