Qt Creator 2.0 and later does not use the compiled version of the debugging helpers anymore on Windows, so C:\Qt\4.6.2\qtc-debugging-helper\debug\gdbmacros.dll is irrelevant. It uses some Python scripts in shared/qtcreator/gdbmacros/*.py instead.

Without seeing the debugger log it's hard to say what's going on.

However, gcc 4.5.0 has some _really_ bad bug in debug information generation, see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44645 to a degree that makes it unusable for debugging. And that's on top of http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44731 that's haunting users also in 4.4.x.