Vauxhall Astra electrical fault

Bit of a strange problem here. But basically its been happening for the past 2 winters. My car has a problem when its cold (5 degrees or less). Firstly, the car has never failed to start. However once I have drove a few mile, the ABS warning light on the dashboard comes on, then a couple minutes later the power steering goes off, then after that all the cars electrics (lights, radio etc.) go off and the car cuts out. The first time this happened in the winter of 2013, I called the AA to pick me up and the car started once they arrived, however the mechanic thought the problem would be the alternator not recharging the battery enough. I had a new alternator fitted however a few days later the exact same problem occurred again. This time I decided to leave the car turned off for a couple minutes then try again, which seemed to work no problem. Since then I have changed the earth straps and the battery, however the problem is still occurring. This is particularly dangerous as I leave for work at 6am, so if I was to break down on a busy road I'd be left without any electrics (including hazard lights) for a good few minutes before I could re-start the car and carry on with my journey. I've had the car in 3 different garages and no one can seem to put their finger on the problem, and nothing shows up on the diagnostics computer. So if anyone has any suggestions I'd be grateful.