I ended up doing something similar. I backed up my steam installed games, and uninstalled steam. Then i went into regedit and searched for silent hunter 5. After removing steam there was a new entry in the registry. I removed all registry mentions and put the DVD in and it worked fine. I reinstalled steam and restored my games. Huge pain in the rear!! But at least now I can enjoy SH5 with all the mods my heart desires.
