Well, I struggled a LOT with this, eventually moving the project folder to a place within my project's hierarchy:

Before:
C:\qt\proj\myproj
C:\qt\proj\qtservice-2.6_1-opensource

After:

C:\qt\proj\myproj
C:\qt\proj\myproj\qtservice-2.6_1-opensource


I changed the include() in myproj.pro to use an absolute path rather than a relative one, and I manually cleaned the entire source tree, removing .o and .moc files myself because it seems they were littered all over the place

I also wrote a .net version of the DEL command, because qmake kept making makefiles that contains "del" as the delete command, but "del" is built into CMD.exe (the dos "shell") and so should be run CMD /C DEL
So "clean"s were never actually cleaning anything because all it would do is say "del: command not found"

Ahh.. Progress is so frustratingly slow!

Doing the manual clean at least solved the "this moc is built with 4.5.3 and youre using 4.6.2" problem.. while I wait patiently for the dev teams to make 4.6.2 work with QtCreator 1.3.81 (you can download the libs, but the mkspecs folder contains some erroroneous files, so you cant use the 4.6.2 libs to make maemo binaries, for pushing to the device within Qt)