The Windows Start Key can be locked or unlocked by pressing the following keys at the same time:
MGK1 & MGK1-K: Function Key and F9. (Fig. 01)
Fig. 01 / MGK1 and MGK1-K Windows Start Lock.
MGK1-RGB: Function Key and Windows Key. (Fig. 02)
Fig. 02 / MGK1 RGB Windows Start Lock.
If the status indicator LED labeled "W" is lit, that means the Windows Start key is locked.