I understand, thanks for clarification! In that case i would like suggested above open a Qt Creator version from the V-Play SDK first before opening a normal Qt SDK Qt Creator. Or alternatively delete the .pro.user file and set up the environment when you changed the Qt SDKs before. Or you could also try Qt Creator 2.5 which is more stable and forgiving when it comes to opening Qt projects of different Qt SDKs.
Cheers and have a nice weekend,