Explain the procedure to test wifi quality and I'll be ready to run those tests for you.
As written already you might open Command-Prompt:
Win+X, launch command prompt (no need for admin)
Then type "ping -t 192.168.1.1"
Assuming 192.168.1.1 is your router IP address, you might find your router/gateway address by typing "ipconfig" on the command line too.
Alternatively just type "ping -t www.google.com" to ping google. However this requires a working internet connection and varying ping-times might occur depending on your Internet connection quality.
Then watch the output for timeouts. The output should look similar to this:
Reply from 192.168.1.1: bytes=32 time<1ms TTL=63
Reply from 192.168.1.1: bytes=32 time<1ms TTL=63
Reply from 192.168.1.1: bytes=32 time<1ms TTL=63
Reply from 192.168.1.1: bytes=32 time<1ms TTL=63
Slight fluctuation in "time" is possible but on LAN/WiFi interface it should not exceed 10ms. If you ping google the value might be between 20ms and 60ms usually.
Test this after reboot, after standby and on battery.
I am at home right now and pinging my router seems to be more stable than at work. This might be partially related to WiFi band overload at work - perhaps the driver just handled it badly. But also here I get occasionally high RTT (time) values. I will monitor again in crowded WiFi network and perhaps let it run for a day or more to watch for more BSOD.
Right now it looks like outdated 12.4 driver is at least more stable. But other issues of Windows 8.1 are a complete no-go too. It looks like it's at least not worth the hassle. If this thread helps somebody with only WiFi issues and nothing else to fix it then it's fine however. Just keep in mind that you might have to disable power management of Wifi driver in device manager and depending on issues (like standby-resume connection) disabling MSI and even 802.11n mode on 4965agn driver might be required.