Enabling MTP in HTC Desire S
An alternative would be to use adb push resp. adb pull to initiate a file transfer between computer and Android device. For this, you don't even need the entire Android SDK on your computer, a few files suffice (see: Is there a minimal installation of ADB?). On a Linux system, you could even mount the Android device using adbfs (see here), and thus access it like a "normal drive" from command line (e.g. via cp/mv) as well as from graphical interfaces.