I was wrong on the first look, there is only one instance of Vegas running. The PID (Process ID) would be different if there were more than one.
You can try ending the the lowest process in the list. This is likely the one holding up your program and causing it to freeze. Tick on the box next to this process, click End Process, and your locked-up program may be brought back to life.
Steve Mann
MannMade Digital Video
http://www.mmdv.com