Take a look at the most common problems:
1. Can't play Halo (other, Xbox)
2. Bungie.net is not responding (MythII, PC)
3. Somebody set up us the bomb. (other, PC)
4. Red games (Myth, PC)
5. Can't find my serial number. (MythII, PC)
6. Games crash on load (MythII, PC)
7. Can't find my serial number. (Myth, PC)
First of all, there are seven links. Second, both 1 and 3 yield interesting answers. Third, at the bottom of the respective answer pages, there is a 32-bit icon. All hardcore Marathoner's should recognize what it is.