I used to update the CM version of my phone every other day. But then after upgrading from 20140620 the Phone app stoped working. It crashed on incoming calls and produced only static noise when calling out. Reinstalling, cleaning cache, cleaning Dalvic cache, flashing new nightlies all didn't help.
The solution was to first flash one of the more stable snapshots releases first (wiping data, cache, Dalvic cache before) and then flashing the wanted nightly release on top of that without wiping data.