if you suspect your downloaded map has virus, you can try to submit it to
virustotal (free), you will see the result of scanning from 40 antivirus.
if you get positive in virus detection, try to download any free antivirus who has detected the virus.
About FH, try to uninstall all, then delete the FH folder, and reinstall it. Try to give more information about why FH doesn't work, it gives any error or simply freezes the computer?