c6 won't load cpr file when double-clicked

if i create a project file, save it, and close down, when I later double click on the cpr file, c6 say it cannot open the file.
after that it shows the recent files, and i load it from the.
using xp sp3

Common problem running C6 under XP. Dragging the cpr file into Cubase should work. Or open from within Cubase using file/open