I have had the same problem. I have a new vista laptop, so I did not already have D2 or LOD on the computer. I was able to install D2 without difficulty but when I attempted to install LOD, I had the same issue with it asking again and again for the D2 "Play CD" which was already in the drive. (I checked the disk on an older PC, not a disk problem). I tried multiple different things but nothing worked. I have tried to play several times. If I run as administrator and change the compability settings, it starts ok which is better than before but then it will freeze. I also had to add all the updates from Blizzard. I have even also installed Direct X 9 to run in addition to 10. Any other helpful hints out there?