I would submit the codectweaktool.exe here..

http://www.virustotal.com/

for a multiscan. If confirmed then delete it (do you use the program?) if not confirmed then wait for a couple of days worth of updates from Malwarebytes to see what happens.

I have both Malwarebytes and a fairly recent version of klite and have had no problems/warnings (as
of my last system malware scan on Sunday)

My version of codectweaktool is 51.49.0.0. I scanned it today w/malwarebytes and it gives the same warning as you got. I submitted it to the multiscan site and it came up totally clean.

I'd say false positive but I'll wait a few days to see what new malwarebyte dat files will do.

Just for the heck of it I ran the tweaktool to see what would happen... nothing unusual... which further points to a false positive.