will dvd studio pro 4.2.1 run on os 10.8?

Probably; one person reported that 4.2.2 runs on 10.8.2.

(103868)

But don't come crying to us when you have problems! Just being a bit snarky. You may be able to get things to work but you will probably not have a dependable system. I recently created a Mavericks boot drive and installed fcp7 along with the other parts of the FCS studio. For the most part everything worked fine, but the occasoinal hiccup when clients were in the room convinced me that working in Snow Leopard was the smarter move. FCS is end of line and eventually I'm going to have to move to Avid or Premiere (or both).