said by SCuervo :

I've had drops maybe a time or two a month with my SB5100 for quite a long time and still have gotten them recently. Quite curious as you say- all the lights are on but no one is home. Going into the setup pages and "reset all defaults" causes it to come back up in little to no time but that was after sitting though a call a year or two back. Not everyone has the ability to fix it and I can imagine it indeed costing many thousands needlessly.