Greeter frozen at boot

[Pat McGowan]

Updated to rc-proposed 174 on MX4
Greeter was hung, no gestures worked and screen not responsive, unity8 running at 30%+ and usc at 10%+
Indicators were not displayed correctly but overlapped
There is no current unity8 log file

Not sure this is helpful:
Unity8:
(gdb) backtrace full
#0 0xb615d620 in syscall () from /lib/arm-linux-gnueabihf/libc.so.6
No symbol table info available.
#1 0xb6312e6a in QBasicMutex::lockInternal() () from /usr/lib/arm-linux-gnueabihf/libQt5Core.so.5
No symbol table info available.
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

USC:
(gdb) bt full
#0 0xb6bf04e0 in poll () from /lib/arm-linux-gnueabihf/libc.so.6
No symbol table info available.
#1 0x00000000 in ?? ()
No symbol table info available.
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Reboot fixed it