Even though it is checked in Preferences>General>Automatically open last project on startup.
While in Preferences>internal for something else, I noticed thet the entry for "Last open project" was blank.
Inserting TRUE here solved the problem.
Do you actually like that option? I can't stand it. It's the first thing i turn off any time i install Vegas, ACID, SoundForge, or etc. If i want to open an existing project i double-click the .veg/.acd/.wav or etc. file. The other 97.2% of the time i always want a blank timeline.