Sometimes if I minimize Vegas, then come back to it, it tells me "An error occurred while
starting playback", and it won't play until I restart my computer.
I'm using Vegas 7.0e on Windows XP SP3, with a Digital Labs CardDeluxe sound card, using the ASIO driver.
I think I recall reading that Vegas dumps the file from cache when minimized to save memory. Maybe you just need to wait a minute after restoring the window before playing it. (Just a guess).
What does the "Details" tab say about the error? When I get that it is usually connected to my soundcard output settings being assigned to another program that is open.