Hello, I also had this same problem although I didn't find a fix to the problem I found a work around so you can play the rest of the campaign.
1. Go to C:\Program Files (x86)\Microsoft Games\Halo 2\maps
2. Copy the map file "00a_introduction" and paste it in the same folder
https://gyazo.com/63bd1ef9e94e811e995c12c8fbcd4f18
3. Change the name of the file "01a_tutorial" to "01a_tutorial1"
https://gyazo.com/b73ed2f098d2d148ae726643c9279617
4. Change the file name of "00a_introduction - Copy" to "01a_tutorial"
https://gyazo.com/d1d74efaea1cca091df2ff9c87730b14
This lets you skip the tutorial part and gives you the beginning cut scene again and will start you off where the tutorial ends.