Try some other hunting-related sites - if you get a similar popup then it is very likely you have an animal-rights version of malware. A way to get rid of it is to do a system restore while in SAFE mode. Assuming you do not have Windows 8, you get safe mode by simply pressing your power button in for 10 seconds. Upon restart, you will have the safe mode option and once in safe mode an option for a system restore will pop up. Unfortunately, however, many malware programs will erase previous restore points. Or you could do an anti-virus scan with whatever program you use.