I've been pursuing a problem on my 2000 STX 900....
Went out and it completely died (after running for about an hour extremely well). She would crank fine but not fire up, so I brought her home.

Looked at the Spark plugs (Looked Fine)
Tested for spark at the plugs (Nothing)
Tested for spark from the Lead wires (Nothing)
Looked at the Ground wire (All is well)
....what's the next thing on the checklist?