I had the exact same issue on other games (not BF4) where it would say pnkbstrb.exe heartbeats stopped after about 30-60 mins of gameplay.
After over a year of trying to find a solution on the web and coming up with a ton of "reinstall pb" instructions that didn't solve the issue, I took a closer look at my services.msc.
When you look at the pnkbstra.exe and pnkbsterb.exe service properties they say the paths to the executables are C:\WINDOWS\system32\PnkBstrA.exe and C:\WINDOWS\system32\PnkBstrB.exe.
So I took a look at that location and lo and behold, they are not there. So I looked around some more in my computer and I found them actually located in the C:\Windows\SysWOW64 directory rather than the system32 directory.
It seemed to me that if the services.msc thinks the files are in system32 when they are not then that may be causing issues with the files being loaded correctly. I copied all PnkBstrA and PnkBstrB files (.exe, .ex0, and .xtr files) to the system32 directory.
I played America's Army: Proving Grounds for about 2 hours tonight without the "heartbeats stopped" message appearing even a single time. Maybe it's dumb luck or maybe this fixed it, but I thought I would share this since I know how frustrating this can be (and because I know it's not just one game - this was first noticed by me on BF3.) Even though I don't play BF4 I wanted to share this on all forums reporting this issue to see if it helps.
