Running free Avast here with no problems. I do exclude the BOINC data directory, but on new machines I've sometimes forgotten that step and not had any obvious problem (without any detailed analysis of crunching efficiency).

Go back to setting just 25 percent of processors aka one thread and see if things improve. I'm running max battery on nexus 7 of 36c, but generally the temp never gets above 29.7. It's now even 24.7 at 1512mhz on 3 cores.

The virus scanners are a frequent source of problems on pcs, so excluding the sandboxed boinc data directory from scanning is most often a solution. Regrettably after installing avast mobile not found a way to exclude anything but general file reading or writing. As the device is not rooted, probably not possible either. Avast themselves say that for certain features to work the droid must be rooted, and that i won't be doing. Anyway, had another signal 11, so it's not the specific av brand that would be responsible.

Those who have android 4.1 and above may want to push in getting the latest 7.4.30 apk build utilizing the p.i.e. model (position-independent-execution ) which has become mandatory for android 5.0 and on, speak lollipop. So far have had the longest non-fail series ever running fahv with this agent release.

Where to get: See post here https://secure.worldcommunitygrid.org/forums/wcg/viewpostinthread?post=476360

What remains open on wcg's part is building an fahv app version for p.i.e. as else this will -not- run on lollipop and future android releases. You'll get 100 percent fail!

Btw, the pie explanations read as if they will prevent the also frequently seen sigsegv/193 errors! All the more reason for wcg to get on with this and port forthwith.

My Kindle is running with all cores, 100% usage and NO errors
now for over a month :-) and I still stream music with Boinc
running with no problems.

Any ideas on my next Android device I should buy? now that
the Kindle is working.