On my Windows XP computer the X button is unresponsive. The PortableApps icon remains permanently in the system tray, but does toggle the menu on and off when clicked. The icon cannot be disabled to allow the USB flash drive to be "safely removed" while the computer is running.
I only learned the proper performance of the menu and the icon when I plugged the drive into another computer. There is one other discrepancy that may or may not be related: the nine items on the right half of the menu do not fit and bleed off to the right - on my computer. Any ideas?