Question about texture error

In my game i have this error all the time:

Could not locate texture: sFlyingmouthProductions/data/shapes/player/crossbow

this error is also found in the starter.fps vanilla build. whats the deal? if i copy any image in the folder it removes the problem, but id love to know whats going on with this one, it causes a ton of errors over time and makes everything tough to debug.

thanks guys,
James Thomas