SlimKat won't return to a phone call gives a black screen.

I have install both releases of SlimKat with the same problem. After I dial a phone number and push send, the screen instantly goes black. The phone call will connect, but the screen just stays black. If I push the home button the screen will flash to the dialer screen and I can see the end call button for only a split second and can never get back to that screen again. I have to reboot the phone or wait until the party I am calling hangs up.
Anyone else having this problem and is there a fix.