Font Rendering using Remote Desktop Connections from a Windows 32Bit client to Windows XP 64bit server

Starting with Qt version 4.6 we have a problem with font rendering when remote connecting from windows 32 bit to a windows 64bit server.
I have attached two screenshots from a small test application, but it can also be reproduced with e.g. Qt designer.
Qt was configured with QMAKESPEC=win32-icc and compiled with the intel icl 11.1 as a 64 bit version. Up to Qt 4.5 everything worked as expected.
Using the application locally or from a different Windows 64bit machine also shows no problem.