PC not seeing Galaxy Tab 10.1 as a a Drive

I am running Windows XP SP3. I install the USB drivers from Samsung Support. I see them all being installed. However, when I connect the Tab 10.1, the PC is not seeing it as a Drive. I have used several different USB 2.0 ports, which all work fine with other devices or flash drives but still the same, despite Powering off Tab, rebooting PC, uninstalling Drivers & reinstalling them. Despite these efforts, I still get conflicting messages that the PC recognises the various devices, is ready to be used but that the hardware may not work properly. I Chatted with a Samsung support rep but he couldn't resolve the problem. Debugging is Off. The Drivers are from GT-p7510_USB_Driver_v1_3_2360_0-Escape.exe. How can I resolve this problem? Thanks.