Hello Dave, i have the same prob as you have and i searched the whole net to get an answer, but nothing.
So i burst my brain for it and i think i get a solution.
The problem i think is the vegas “veg” file. probably not for everyone but for my scenario.
The veg file must have a michmatch information content in it selfs, i think.
For my new projekt i opened an old other project because some things i can use for my new project. So i fill all in work in the old project, modivied it and safed it as a new project. And this must be the problem. Too much information of unused tracks and offlined files in this project, while all is stocked in this new file what orig was an old file. So i searched for a way to edit the veg file in a text editor for deleting some old information. But that doesn´t work and the file is corrupeted after that.
A chance is to open a new project in another opened Vegas window (important).
So follow my steps.
1. open Vegas with the (bad) project.
2. open another vegas with a new project and the propperties you must have to.
3. create the same sume of tracks in the new project of the second opened vegas.
4. marker all sequences of one track. than copy that mareked track and drag it into one of the new track of the second vegas.
5. make this with every track until all is the same asin the old project.
6. safe this new project in the second vegas with a new name and for safeness on a other location on your hdd (create a new folder, that must suffices).
7. Close all vegas and start vegas with the new project.
8. All must work.
Why? you edit the veg file by this workflow. yet you have only the new informations stored in the veg file, no more old michmatch information.
Try it, for me it works well.
regards
Guido