Hi, I downloaded again and again, Vegas movie studio 11

(and once even to another computer)

but when I finish downloading successfully

 and arrive to open, it always writes me the same message:

" Vegas movie studio 11  is already installed. If you want to reinstall the application please uninstall the existing version before installing".

I am so frustrated I cleared all the installations but still nothing happens

 even when I downloaded to another computer!

this thing started happening after I accidentally deleted some Vegas files 

Since then i can't download again, although I believe I already cleared all vegas files.

 And it's happening also on another computer on which there was never any Vegas.

WHAT CAN I PLEASE DO?   THANX.