It would appear you installed my Shadow d20 houserules file at some point and then "manually" removed part of it? Or maybe you removed the Community Pack but not my houserules files?
Start HL and press OK through the error. Then go to
Tools->Manage Third Party Updates and delete "
Shadow d20". If for some reason that is not their to delete then you need to go into the data folder and manually remove all the "
Shadow d20 - " named files.