black screen white pointer

gnome-screenshot by dash results in spinning cursor and then nothing

gnome-screenshot by commandline ...results in black screen with white pointer and nothing else. Have to alt-f1 to log into a new shell to find & kill gnome-screenshot process which gets unity back.

once i kill the process further instances of gnome-screenshot work fine.

errors in the meanwhile:
Error creating proxy: GDBus.Error:org.freedesktop.DBus.Error.LimitsExceeded: Failed to determine seats of user "1001": Too many open files (g-dbus-error-quark, 8)

desktop environment: unity 7.5.0+17.04.20170407.1-0ubuntu1
xorg : 1:7.7+16ubuntu3
ubuntu: 17.04 zesty
Linux eva1 4.10.0-21-generic #23-Ubuntu SMP Fri Apr 28 16:14:22 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

       *-display
             description: VGA compatible controller
             product: Intel Corporation
             vendor: Intel Corporation
             physical id: 2
             bus info: pci@0000:00:02.0
             version: 04
             width: 64 bits
             clock: 33MHz
             capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
             configuration: driver=i915 latency=0
             resources: irq:128 memory:de000000-deffffff memory:c0000000-cfffffff ioport:f000(size=64) memory:c0000-dffff

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: gnome-screenshot 3.22.0-1ubuntu1
ProcVersionSignature: Ubuntu 4.10.0-21.23-generic 4.10.11
Uname: Linux 4.10.0-21-generic x86_64
ApportVersion: 2.20.4-0ubuntu4.1
Architecture: amd64
CurrentDesktop: Unity:Unity7
Date: Tue May 30 19:48:41 2017
InstallationDate: Installed on 2017-04-18 (42 days ago)
InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
JournalErrors:
 Error: command ['journalctl', '-b', '--priority=warning', '--lines=1000'] failed with exit code 1: Hint: You are currently not seeing messages from other users and the system.
       Users in the 'systemd-journal' group can see all messages. Pass -q to
       turn off this notice.
 No journal files were opened due to insufficient permissions.
SourcePackage: gnome-screenshot
UpgradeStatus: No upgrade log present (probably fresh install)