When I start my 2007 S60 2.5 T AWD the driver mirror starts lowering and the driver side back window goes down. No windows or mirrors then work. If car is turned off and key in the accessory position the mirror and windows work fine. Start the car up again and the same thing happens, one window lowers and other windows do not work and power mirror motor starts lowering and will not stop, mirror then keeps clicking in lower position as motor does not shut off.

 

Are your windows auto up and down. If so try resetting them (see manual).
Next try new batteries in your key remote. I have had some pretty weird things go on when my remote batteries are low.
Worst case could be an electrical short circuit.
Try these first steps first, they are cheap and easy.

 

I have an interesting solution to the module not working. A friend brought me XC70 to look at as his driver's window and mirror control switches were not working. I checked that it was plugged in properly and rebooted the computer by disconnecting/reconnecting the battery. Still no luck. I connected the car to my OBD on my laptop but I could only read generic sensors. I told him he will have to take it in to a Volvo workshop that can do a full check on errors. He took it to sweedspeed in Cape Town, South Africa. They diagnosed the faulty window control module and said they will look for a second hand module as they are probably expensive. A day later they phoned my friend to say that they found the problem with another car and it was a blown fuse for the under dash courtesy lights. He then checked his lights under the dash and they were not working, replaced the fuse and bazinga, the lights and window module worked. The module and courtesy lights share the same 2.5A fuse!
I hope this post helps some body out there with the same problem.