It appears to be a Halo 2 bug, not a vista bug. There maybe a patch for
it from MS, not sure tho. It happens to those who tried to use the
Windows XP hack too (I.E. - Running Halo2 on XP)
Many have encountered this issue, there are more post on these forums
about it, try the search function.
Side Note: IMHO, Halo2 for the PC just plain sucks when compared to
other PC shooters. Hey, Halo 2 great for a console shooter (most
console shooters truly suck compared to PC shooters). Halo 2 has good
gameplay and story but it just pales when compared to things like Quake,
UT, CoD and others IMO. Not to mention, MS did NOTHING to update Halo 2
itself visually for the PC, no updated graphics, no DX10 or anything.
It's just plain ugly on the PC. One the worst looking games on the PC
right now, it looks older that it actually is (and it is old). Original
UT'99 looks better IMO. Halo 2 looks better on the original X-Box than
the PC I think.
But anywho, I hope you can get it to work, few things are as frustating
as not being able to finish a game you are well into because of