Search the registry for entries named "fraps." Press F3 to repeat the same search in the last direction specified. Make sure you're deleting fraps entires though... deleting things in the registry can be very dangerous.
Alternatively, you can run
Regmon then launch the installed fraps exe. It should tell you which registry keys it's trying to access. I'd recommend deleting all of the ones listed, deleting all of the files and then completely reinstalling the application.
I highly recommend you try running RegMon before resorting to aimlessly poking through the registry with little gide other than the 5 byte string "fraps"...
Newby is fully correct (morally and lawfully), though. I'm sure we're all guilty of pirating to some degree, but this isn't the place to advertize it.