A possible solutiion is to open the Task Manager (Ctrl+Alt-Del) and under Background Processes click on the End Task button fior any Vegas Pro entries. This seems to be a common 'time-to-time' problem with Windows 11.
I may have come up with something. For me, the problem with starting Vegas was caused by the firewall in ESET antivirus. I manually set the ESET firewall rule for Vegas200.exe (I'm using Vegs 20) to ALLOW for input and output and it seems to have helped.