Six months ago, I purchased a '99 S-70 with 72K miles from a "middle dealer." At least once every 3-4 weeks, my wife will turn the key and nothing will happen. She's tried moving the gearshift (in case it was the neutral safety switch) and many other "superstitious" actions. Sometimes it will start after 15 minutes, sometimes it has to sit overnight. When the key is turned, all of the "dummy lights" go on, but in the ignition position, there is a click and a faint "whir" for 2 seconds, then nothing. We've had it back to the dealer from whom we purchased it and to our own mechanic, but it starts for them every time, making it impossible to diagnose. My wife teaches in a "rough area" of a big city, which is why I wanted a "reliable" Volvo. Any insight will be greatly appreciated.

Has anyone heard of this before? Any thoughts on remedies?