Ok,, all has been pretty well with me and vegas 8c,, till today. Vegas wont' boot, just hangs on initializing directx.. Running vista on a quad,, nothing at all new installed,, ran perfect yesterday. Did a system restore, and new vegas install , nogo. any ideas?
Sounds like one of the plugins got hosed, or a new one got installed that is incompatible.
For starters, find your "Shared Plug-Ins" folder (location varies with OS), and try renaming the plugins one at a time until Vegas starts. Then you could leave the offending plugin renamed and reinstall from the installation disc.
A habit I acquired a long time back in Sonic Foundry days --
Every time I do a SMS install, upgrade, or add plugins, I back up the Shared Plug-Ins folder. That way, I've got something to go back to in case of an unintentional deletion or muck-up like what happened to you.