I also have a stack trace that may or may not be related: 

[20151.429335] [drm:intel_pipe_config_compare] *ERROR* mismatch in adjusted_mode.flags (expected 1, found 0)
[20151.429345] ------------[ cut here ]------------
[20151.429411] WARNING: CPU: 2 PID: 1707 at /build/buildd/linux-3.11.0/drivers/gpu/drm/i915/intel_display.c:8292 check_crtc_state+0x58f/0x9c0 [i915]()
[20151.429415] pipe state doesn't match!
[20151.429418] Modules linked in: usb_storage(F) hid_generic hidp hid ipt_MASQUERADE(F) iptable_nat(F) nf_nat_ipv4(F) xt_CHECKSUM(F) iptable_mangle(F) bridge(F) stp(F) llc(F) pci_stub vboxpci(OF) vboxnetadp(OF) vboxnetflt(OF) vboxdrv(OF) ebtable_nat(F) ebtables(F) parport_pc(F) ppdev(F) rfcomm bnep joydev(F) binfmt_misc(F) nfsd(F) auth_rpcgss(F) nfs_acl(F) nfs(F) lockd(F) sunrpc(F) fscache(F) ext2(F) uvcvideo videobuf2_vmalloc videobuf2_memops x86_pkg_temp_thermal videobuf2_core videodev intel_powerclamp coretemp kvm_intel(F) kvm(F) arc4(F) iwldvm mac80211 ip6t_REJECT(F) xt_hl(F) ip6t_rt(F) nf_conntrack_ipv6(F) nf_defrag_ipv6(F) btusb bluetooth ipt_REJECT(F) xt_limit(F) xt_tcpudp(F) xt_addrtype(F) nf_conntrack_ipv4(F) microcode(F) snd_hda_codec_conexant psmouse(F) iwlwifi serio_raw(F) snd_hda_intel snd_hda_codec cfg80211 snd_hwdep(F) wmi snd_pcm(F) snd_page_alloc(F) snd_seq_midi(F) snd_seq_midi_event(F) nf_defrag_ipv4(F) xt_conntrack(F) snd_rawmidi(F) snd_seq(F) ip6table_filter(F) tpm_tis ip6_tables(F) thinkpad_acpi nf_conntrack_netbios_ns(F) nvram(F) nf_conntrack_broadcast(F) nf_nat_ftp(F) nf_nat(F) nf_conntrack_ftp(F) nf_conntrack(F) iptable_filter(F) ip_tables(F) x_tables(F) snd_seq_device(F) snd_timer(F) mac_hid lpc_ich snd(F) mei_me mei soundcore(F) lp(F) parport(F) dm_crypt(F) crct10dif_pclmul(F) crc32_pclmul(F) ghash_clmulni_intel(F) aesni_intel(F) i915 aes_x86_64(F) lrw(F) gf128mul(F) glue_helper(F) ablk_helper(F) cryptd(F) video(F) i2c_algo_bit sdhci_pci drm_kms_helper sdhci ahci(F) libahci(F) drm e1000e(F) ptp(F) pps_core(F)
[20151.429568] CPU: 2 PID: 1707 Comm: Xorg Tainted: GF       W  O 3.11.0-12-generic #19-Ubuntu
[20151.429572] Hardware name: LENOVO 4180J4C/4180J4C, BIOS 83ET76WW (1.46 ) 07/05/2013
[20151.429576]  0000000000000009 ffff8801925bd898 ffffffff816e547a ffff8801925bd8e0
[20151.429583]  ffff8801925bd8d0 ffffffff81061dbd ffff88019534f6d0 0000000000000001
[20151.429589]  ffff88018fcdc000 ffff88019534f000 ffff88018fcdc478 ffff8801925bd930
[20151.429595] Call Trace:
[20151.429610]  [<ffffffff816e547a>] dump_stack+0x45/0x56
[20151.429620]  [<ffffffff81061dbd>] warn_slowpath_common+0x7d/0xa0
[20151.429627]  [<ffffffff81061e2c>] warn_slowpath_fmt+0x4c/0x50
[20151.429667]  [<ffffffffa015d9ef>] check_crtc_state+0x58f/0x9c0 [i915]
[20151.429707]  [<ffffffffa0168bf3>] intel_modeset_check_state+0x2c3/0x770 [i915]
[20151.429740]  [<ffffffffa0169135>] intel_set_mode+0x25/0x30 [i915]
[20151.429772]  [<ffffffffa0169982>] intel_crtc_set_config+0x742/0x910 [i915]
[20151.429807]  [<ffffffffa0071f8d>] drm_mode_set_config_internal+0x5d/0xe0 [drm]
[20151.429838]  [<ffffffffa00749c7>] drm_mode_setcrtc+0xf7/0x650 [drm]
[20151.429872]  [<ffffffffa015ef72>] ? intel_crtc_load_lut+0xd2/0x170 [i915]
[20151.429898]  [<ffffffffa0065212>] drm_ioctl+0x532/0x660 [drm]
[20151.429918]  [<ffffffff811b8ba5>] do_vfs_ioctl+0x2e5/0x4d0
[20151.429927]  [<ffffffff811a91f1>] ? __sb_end_write+0x31/0x60
[20151.429934]  [<ffffffff811a6d82>] ? vfs_write+0x172/0x1e0
[20151.429942]  [<ffffffff811b8e11>] SyS_ioctl+0x81/0xa0
[20151.429950]  [<ffffffff816f521d>] system_call_fastpath+0x1a/0x1f
[20151.429955] ---[ end trace ad96f94859530fca ]---