I hope this doesn't throw everyone for a loop but, just like you all, I'm experiencing the same problem. Oddly enough, my wife's laptop (which is equipped with an Advanced-N 6250) has never experienced any of these issues in the 3 years we've owned it (Dell XPS 1645). Her and I both are using the latest wireless adapter drivers from Intel. The difference is she is using the Advanced-N 6250 on a Windows 7 64bit platform compared to my Advanced-N 6235 (MSI GT70 Laptop) on a Windows 8 64bit platform. Same location of the house (different times of course)
My laptop originally came with a Wireless-N 2200. After experiencing these exact results, I opted to upgrade to the 6235 hoping that would fix the problem. No dice.
I just wanted to share. I'm thinking I'll try and disable the Wireless N and see what results I get.