Start Menu not functioning

When users with laptops are outside of the network, and logon using their domain account, their start menu will not display the “all programs” contents. All other icons work: control panel, printers, and even the recent program shorcuts work. You hover over all programs and it will not display. This has occured on many Win2K and XP machines only if they use their domain account instead of their local account on the laptop.

Any ideas?