I get the same error....I am able to open the file from a different location and run all the disks. HOWEVER!!!!!! When you have to install the 1st disk again at the end it does not finish the loading. You will get the Library not registered error again. It does appear that the game is loaded. You will have an icon on the desk top but then you will get a CoDMP.exe error and cannot open file error since it appears to be in the wrong folder ect....It is extremely frustrating. I am in a clan on COD2 and most of us that updated or purchased a new computer with Windows 7 have not been able to play anymore.
Most folks keep giving very generic information on how to fix the issue. Some folks complained and complained and then comeback with "NVM I fixed it" but them do not share what they did to fix the issue for others who have the same problem.