Text (US+errata): 1/1. ; {1}{W},{Tap}: Target creature becomes an enchantment and loses all abilities until a player casts a creature spell. [Oracle 2009/07/08]
The creature stops being a creature (or any other permanent type) and is just an enchantment with no abilities. [Urza's FAQ 1998/10/05]
A creature spell is any "Creature" or "Artifact Creature" spell. [D'Angelo 1999/05/01] Older cards of type Summon are also Creature cards.
Note - This card was creature type "Townsfolk" until Oracle 2007/10/01, when it became "Human".
