I had that problem yesterday too. A complete shutdown and restart fixed it for me.
Is there a path to go from a VP13 project to a VP10 project - that version seems to work.
Open both Pro 10 and Pro 13. Copy everything from the Pro 13 timeline(s) to the Pro 10 timeline(s). Save it with a new project name.
Be advised that some things like Track Motion will not work and will have to be redone.
I managed to guess my way around the site by looking at the links and got english back as site languahe, yay. Noticed an admin remark in something not related, so, I've started VP13 explicitly as administrator, maybe that helps, though until now I've run it normally, well with an admin user account. See if it renders the project that crashed it, I would hate to have to go without Vegas.
Could be. But you'll always need an effect here or there.
Render still crashes, used a video curves effect in that one. Hardly a mix of plugs. I could probably work around it, but it's a lot of work and time lost.