*D3 goes black screen for 2-5 second periods every so often, the frequency is random, could be 5 times in a few minutes or once in a 4 hour play period.
*D3 black screen "Alt-tabs" the game, then upon resuming tanks the FPS from 150, to 9, making the game lag horribly and makes it unplayable.
* this effects anyone with a Gforce GTS250 video card. I know some other cards are having the issue just not sure which ones specifically as this is the card I run and have noticed most frequently mentioned.
For some the solution was easy for others it was difficult, I personally had to do 3 different things to make my game stable and run smoothly.
*Set my game resolution to 1280X720 (16:9)
*Cap my FPS at 70, background FPS at 8
*Download the Nvidia Control Panel from Nvidia's website, (google works too) once installed Look at the menu list on the left side of the program, go to Performance then Device Settings. Once here click on the Custom button just above the Clock Mhz value sliders.
Customize each slider down by 50Mhz, apply and save these settings.
Open D3 and run as normal, yes the game will look more pixilated from a lower rez and might run slightly (very) slower due to a lower clock speed, but its the only thing I've found so far that works for a solution.
I personally had to do all 3 of these to get mine working, but I've heard of some folks only needing to do one or two of them to have the same effect. Also as noted by blizzard make sure you have your beta client uninstalled to be on the safe side.
Using this method I played half my day yesterday without any interruption.
Best of luck and hope this helps!