An ignition switch and an ignition module are not the same thing. The ignition switch is what you put the key in and your symptoms point to that. An ignition module would stop your engine but would not make your windows or dash lights quit.
Before you reconnect the battery follow the positive battery cable to the starter relay. On one of the terminals there should be 3 or 4 small wires held on by a nut. These are the fuse links and one of them provides power to the ignition switch. Make sure you have a clean tight connection there.
If the random dying with the A/C and window problem is accompanied by lack of the dashboard warning lights working then the ignition switch is a good suggestion.
The switches can fail over time mainly due to a worn cabin blower motor. An aged motor draws a lot more current (meaning the amount of electricity) and that current is routed through the switch instead of a relay. Poor design.
After 2 switch failures I added a relay and wired it up so the blower motor current would bypass the switch.
The ignition modules are also prone to heat failure; especially with the onset of warmer weather.
I went through several modules on my old Sable and cured that problem with a modification. The module was mounted on a piece of finned aluminum heatsink and mounted inside of the air cleaner housing. The wiring pigtail was then extended and heat issues became a thing of the past. Whenever the engine was running the module was cooled down considerably courtesy of the intake air and heatsink.
This is why the automotive engineers get paid big bucks; to build in flaws to tick the motoring public off. 
This may be a silver bullet if I remember correctly. It’s been over 10 years. I had a Taurus get towed in with similar complaints…car would die and power windows would be inoperative at the same time. If the windows came back to life, the car would also start and run. Being quite lazy, I didn’t do any testing at first before spending 20 minutes reading the entire car wiring diagram to find something in common between these 2 systems. Both the fuel pump and the power windows share a “gang ground” located if I recall under the carpet around the driver’s seat. A corroded poor connection caused intermittent and simultaneous loss of power windows and fuel pump.