Lenovo X1 Carbon 2015 only boots on second attempt on 15.04 - but always fails on first boot

After Kernel upgrade last week my lenovo x1 carbon 2015 fails to boot on first attempt (with nice graphics). It is configured with full disk encryption so I usually see a nice ubuntu screen with passphrase input.

Since last week I see just a black screen. When I switch to console with Ctrl-Alt-F1/F2.. I see mysterious thick white lines in the upper left corner.

When I power off and reboot I can then boot into ubuntu with a "failsafe" mode as it does not show nice graphics but just plain text to enter my passphrase. After this everything runs fine as usual.

I think it must be a graphics driver which doe not work and fails.

# lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Broadwell-U Integrated Graphics (rev 09)
# lshw -c video
  *-display               
       Beschreibung: VGA compatible controller
       Produkt: Broadwell-U Integrated Graphics
       Hersteller: Intel Corporation
       Physische ID: 2
       Bus-Informationen: pci@0000:00:02.0
       Version: 09
       Breite: 64 bits
       Takt: 33MHz
       Fähigkeiten: msi pm vga_controller bus_master cap_list rom
       Konfiguration: driver=i915_bpo latency=0
       Ressourcen: irq:48 memory:f0000000-f0ffffff memory:e0000000-efffffff ioport:3000(Größe=64)
# uname -a
Linux thinkpad 3.19.0-30-generic #33-Ubuntu SMP Mon Sep 21 20:58:04 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

I am runnng ubuntu 15.04

How can I fix this problem?