Scan takes a long time to finish

??? Ok, I am not a techie, so I don’t understand MOST of what I read in these forums… BUT: when I click on the buttons for Comodo to scan my hard drive, it takes 10 to 12 HOURS and never completes the task. I was sure this was not right so I uninstalled the program and reinstalled it from a fresh download. Still have this problem. There is no error message or any particular “picture” to show - it just seems to get hung up.

1 Gig ram, 30% of memory used, no music files or movies, Windows XP SP2