Qt Creator on Windows XP: The procedure entry point strlen could not be located in the dynamic link library msvcrt.dll

I've installed latest official released Qt on both, Windows 7 and Windows XP. Both are on the latest VirtualBox with 3D support. On Windows XP, during start of QtCreator there is message box (several times) saying "The procedure entry point strlen could not be located in the dynamic link library msvcrt.dll" but QtCreator starts eventually and everything seems to work (including Welcome). On Windows 7 there is no such message, but I need to run QtCreator with -noload Welcome, because some part of window is not refreshing (menu partly visible). I also tried to "repair" mentioned DLL by running
sfc /scannow
but situation was like on Windows 7 + I was unable to run example program (cube) that was built before "repair", even after rebuilding it (successfully) and after re-installation of Qt, it keeps crashing.
Why QtCreator works better on Win XP when it can't find strlen in msvcrt.dll?