if you go to linuxiso.org there's a link to a short how-to on how to check md5sums. Its a real timesaver when you know for certain the isos you burned are good.
If they are, do like the suggestion above....try a text install, bare-bones and add the packages you need one at a time...
Personally I've had 2 smooth installs with 9.1 and 3 completely screwed up ones...the screwed up ones were the ones where a bug popped up at one point or another (and one where I screwed it up myself without any help from anyone else
)...and I just reinstalled. But once you have it in, its worth it...you'll see.