Hark is a simple Word Macro virus. Infected documents have macros called "AutoOpen" and "Harkone".
This virus has an interesting activation routine. On 1st of June the virus maximizes all active windows, changes the font size to 60 and insert the test "HARKONE" and "NJ [SLAM]".
SLAM is a name of a virus-writing group.
Disinfection & Removal
Technical Details: Katrin Tocheva, F-Secure