Check your install files against the checksum values I posted in the
Installation freezes topic. That will help determine if the problem happened during download (in which case re-downloading just the problem file(s) should fix) or on install.
Use the freeware (no install required) program
DVDsig for this, which I've included along with the checksum file for my download folder:
DVDSig-DivDragonComm.zip (9KB). Extract the zip file into your download folder, run the DVDSig program and click on Verify.
If the files themselves are ok, then maybe reboot, shut down any non-essential programs that may be causing a conflict (such as anti-virus) and run the install program as administrator, installing the game to a non Program Files install path.
If there are 'corrupt' files identified, there was either a problem when you downloaded them, or Larian may have updated the files after I downloaded them.