That's what I am using, V8a, I downloaded it a day or so ago and installed it in my V7 folder on top of V7. Should I have uninstalled V7 first?
There was no warning message that I should do so.
I downloaded it a day or so ago and installed it in my V7 folder on top of V7
That's probably your problem. You should have left the Vegas 7 folder along (Vegas 7 and 8 can both co-exist on your system) and let it install in the default Vegas Pro 8 folder.
That's it!
Uninstalled V7, uninstalled V8, warm boot, reinstal V8 (in my own folder) and Ahh Misuri Sana Bwana, iko mpg1 mpg2 - the whole shebang. Happy happy!