If you look this forum you will people saying they have 'white flashes' of the screen, especially when going to the inventory screens. I tried all the solutions as did others about changing to software rendering, disabling this and that, the unofficial patch, mp3 sounds etc and while it lessened it never went away.

I found something for me that made it go away completely.

The Rocksmith "microphone" usb device. There's a PC game called Rocksmith that comes with a USB cord to plug in an electric guitar and it detects your notes similar to the guitar hero games but a real guitar and full tabs. It does this by treating the guitar as a microphone and there are several driver options you have to choose to allow it work properly.

Unplugging the cable (which removes the microphone) made all the white flashes disappear. I don't know if its something to do with sound interrupts (anyone remember their old roland IRQ number?) or what but with it unplugged everything is working smoothly.

Just thought I'd share and hope it helps someone.