At first glance it appears to want to uninstall Vegas before proceeding with a new install.

Are you upgrading from an eval or previous version?

Does Control Panel --> Add Remove Programs list anything for Vegas?

Any hints in the Windows Event Log?

Depending on your Windows Update version, maybe cross-check Windows Securiity --> Protection History if any folders are blocked. This one did bite me years ago.

Do you have adequate available disk space?

Also, that's a lot of temp files. I usually routinely blow those out -- if they are not in use. I think Disk Cleanup will take care of some.

BTW, I am confused. Your other post suggests that Vegas 22 is up running but gacking on your media. Which is it?