XP Home Help and Support refuses to play

Machine is a new ACER Aspire 2000 (1.6 GHz Centrino, 512KB, 60 GB Ultra ATA 100). After no initial problems, the Help & Support link on the Start Menu now refuses to work. Have fully updated and patched WinXP Home, AVG AV, Zone Alarm firewall, no bots or trojans etc. Registry Mechanic, System Mechanic and several other diagnostic tools show nothing wrong. Seems simple, but the answer has so far escaped me. Can anyone help?