Legacy wont start - warning lights on

[Steve Fowler]

My 2007 R spec b 3.0L Legacy sometimes won't start. The engine warning light and ABS light come on and the cruise control light flashes. The only way to start the car seems to be to rock it from side to side and switch the ignition on and off several times. After sometimes 5 minutes, but more often than not 30, I can get the car to go. The car sticks in sport mode and the cruise control won't work under these conditions. This happens sporadically and my Subaru dealer is at a loss to know what is causing it. Sometimes, months will go by with no problem then it'll happen several times in a row.

The problem is unaffected by weather or external temperature but does seem more likely to happen if the car has been driven fast. Any ideas ?