<< yup, its an explorer. 🙁
Duno how it died, the "laser" doesn't come on anymore. >>
The diode could have burnt out, it's possible that's all that's wrong with it. MS has a pretty good policy on replacement though so I wouldn't worry.
I had a problem with my MS explorer mouse too but I think it has more to do with my os(at least I hope that's the reason). What do they usually ask you for when you request an RMA #? The numbers on the bottom of my mouse have mostly worn off so I can't tell the serial number.