Tomek, thank you for reporting this and helping make Ubuntu better. Please execute the following command, as it will automatically gather debugging information, in a terminal: apport-collect 1460551
** Package changed: linux-lts-utopic (Ubuntu) => linux (Ubuntu) ** Changed in: linux (Ubuntu) Importance: Undecided => Low ** Changed in: linux (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1460551 Title: Random screen locking Status in linux package in Ubuntu: Incomplete Bug description: Random screen locking happens about once an hour. Mouse is not responding, keyboard is, but GUI does not respond. To overcome the problem I have to switch to terminal with ctrl+alt+1 and go back. In dmesg I can see: [ 68.509976] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.510021] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.510044] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.510064] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.510083] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.510102] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.510134] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.510154] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.510644] ACPI Warning: \_SB_.PCI0.RP05.PEGP._DSM: Argument #4 type mismatch - Found [Buffer], ACPI requires [Package] (20140424/nsarguments-95) [ 68.615945] vgaarb: this pci device is not a vga device $ dmesg | grep vgaarb [ 0.524324] vgaarb: setting as boot device: PCI:0000:00:02.0 [ 0.524325] vgaarb: device added: PCI:0000:00:02.0,decodes=io+mem,owns=io+mem,locks=none [ 0.524328] vgaarb: loaded [ 0.524329] vgaarb: bridge control possible 0000:00:02.0 [ 1.498735] vgaarb: device changed decodes: PCI:0000:00:02.0,olddecodes=io+mem,decodes=io+mem:owns=io+mem [ 5.667900] vgaarb: this pci device is not a vga device [ 6.409112] vgaarb: this pci device is not a vga device [ 68.506178] vgaarb: this pci device is not a vga device [ 68.615945] vgaarb: this pci device is not a vga device $ lspci 00:00.0 Host bridge: Intel Corporation Haswell-ULT DRAM Controller (rev 0b) 00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 0b) 00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev 0b) 00:14.0 USB controller: Intel Corporation Lynx Point-LP USB xHCI HC (rev 04) 00:16.0 Communication controller: Intel Corporation Lynx Point-LP HECI #0 (rev 04) 00:19.0 Ethernet controller: Intel Corporation Ethernet Connection I218-LM (rev 04) 00:1b.0 Audio device: Intel Corporation Lynx Point-LP HD Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation Lynx Point-LP PCI Express Root Port 1 (rev e4) 00:1c.3 PCI bridge: Intel Corporation Lynx Point-LP PCI Express Root Port 4 (rev e4) 00:1c.4 PCI bridge: Intel Corporation Lynx Point-LP PCI Express Root Port 5 (rev e4) 00:1c.5 PCI bridge: Intel Corporation Lynx Point-LP PCI Express Root Port 6 (rev e4) 00:1d.0 USB controller: Intel Corporation Lynx Point-LP USB EHCI #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation Lynx Point-LP LPC Controller (rev 04) 00:1f.2 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 04) 00:1f.3 SMBus: Intel Corporation Lynx Point-LP SMBus Controller (rev 04) 01:00.0 SD Host controller: O2 Micro, Inc. SD/MMC Card Reader Controller (rev 01) 02:00.0 Network controller: Intel Corporation Wireless 7260 (rev 73) 03:00.0 3D controller: NVIDIA Corporation GF117M [GeForce 610M/710M/820M / GT 620M/625M/630M/720M] (rev a1) Dell Latitude E5540 SMBIOS 2.7 present. Handle 0x0000, DMI type 0, 24 bytes BIOS Information Vendor: Dell Inc. Version: A11 Release Date: 02/02/2015 Address: 0xF0000 Runtime Size: 64 kB ROM Size: 14336 kB Characteristics: PCI is supported PNP is supported BIOS is upgradeable BIOS shadowing is allowed Boot from CD is supported Selectable boot is supported EDD is supported 5.25"/1.2 MB floppy services are supported (int 13h) 3.5"/720 kB floppy services are supported (int 13h) 3.5"/2.88 MB floppy services are supported (int 13h) Print screen service is supported (int 5h) 8042 keyboard services are supported (int 9h) Serial services are supported (int 14h) Printer services are supported (int 17h) ACPI is supported USB legacy is supported Smart battery is supported BIOS boot specification is supported Function key-initiated network boot is supported Targeted content distribution is supported UEFI is supported BIOS Revision: 4.6 Handle 0xDEE1, DMI type 13, 22 bytes BIOS Language Information Language Description Format: Long Installable Languages: 1 en|US|iso8859-1 Currently Installed Language: en|US|iso8859-1 $ lsb_release -rd Description: Ubuntu 14.04.2 LTS Release: 14.04 ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.16.0-38-generic 3.16.0-38.52~14.04.1 ProcVersionSignature: Ubuntu 3.16.0-38.52~14.04.1-generic 3.16.7-ckt10 Uname: Linux 3.16.0-38-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.14.1-0ubuntu3.11 Architecture: amd64 CurrentDesktop: Unity Date: Mon Jun 1 09:28:38 2015 EcryptfsInUse: Yes InstallationDate: Installed on 2015-05-28 (4 days ago) InstallationMedia: Ubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1) SourcePackage: linux-lts-utopic UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1460551/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp