WampServer

I've had Wamp with php versions 5.2x and 5.3x installed and working. All of a sudden, something has changed that is preventing me from switching to 5.3. I've tried re-installing that version - same thing. When I switch the apache version, the log shows that it was switched. But when I look at the version through Wamps GUI, it stays on the old version. Same with php. I've tried rebooting, stoping and starting the services - no chnage. Does anyone have any idea what the problem might be?

Using wampserver 2.1
Windows 7