No, it definitely isn´t the Hardrive sleep. Today LimeWire crashed while using it and my hard drive definitely wasn´t asleep.

I also did some tests where I let my harddrive spin down and switched to limeWire then. It worked perfectly and my HardDrive spun up again.

Although I can´t confirm that when LimeWire is in the backround, the Drive spinns down and LimeWire trys to read from it.. it doesn´t lead to a crash.

cu Martin

p.s.: (Sorry for the bad english)