It's very unlikely to relate to compiz. After latest update message about compiz disappeared but [drm:i915_getparam] *ERROR* Unknown parameter 6 persists. I found strange thing in Xorg.0.log: repeating [ 55.180311] (II) intel(0): I2C bus "CRTDDC_A" initialized. [ 55.181073] (II) intel(0): I2C bus "CRTDDC_A" removed. [ 55.220560] (II) intel(0): EDID for output VGA [ 55.274699] (II) intel(0): EDID for output LVDS [ 55.274721] (II) intel(0): Manufacturer: AUO Model: 2451 Serial#: 0 [ 55.274732] (II) intel(0): Year: 2005 Week: 1 [ 55.274741] (II) intel(0): EDID Version: 1.3 [ 55.274749] (II) intel(0): Digital Display Input [ 55.274758] (II) intel(0): Max Image Size [cm]: horiz.: 30 vert.: 23 [ 55.274774] (II) intel(0): Gamma: 2.20 [ 55.274791] (II) intel(0): No DPMS capabilities specified [ 55.274803] (II) intel(0): Supported color encodings: RGB 4:4:4 YCrCb 4:4:4 [ 55.274813] (II) intel(0): First detailed timing is preferred mode [ 55.274821] (II) intel(0): GTF timings supported [ 55.274829] (II) intel(0): redX: 0.580 redY: 0.340 greenX: 0.310 greenY: 0.550 [ 55.274847] (II) intel(0): blueX: 0.155 blueY: 0.155 whiteX: 0.313 whiteY: 0.329 [ 55.274862] (II) intel(0): Manufacturer's mask: 0 [ 55.274871] (II) intel(0): Supported additional Video Mode: [ 55.274879] (II) intel(0): clock: 65.0 MHz Image Size: 304 x 228 mm [ 55.274909] (II) intel(0): h_active: 1024 h_sync: 1048 h_sync_end 1184 h_blank_end 1344 h_border: 0 [ 55.274923] (II) intel(0): v_active: 768 v_sync: 771 v_sync_end 777 v_blanking: 806 v_border: 0 [ 55.274967] (II) intel(0): Ranges: V min: 0 V max: 200 Hz, H min: 0 H max: 200 kHz, [ 55.274980] (II) intel(0): AUO [ 55.274988] (II) intel(0): B150XG02 V4 [ 55.274996] (II) intel(0): EDID (in hex): [ 55.275010] (II) intel(0): 00ffffffffffff0006af512400000000 [ 55.275023] (II) intel(0): 010f0103801e17780a87f594574f8c27 [ 55.275036] (II) intel(0): 27505400000001010101010101010101 [ 55.275048] (II) intel(0): 01010101010164190040410026301888 [ 55.275061] (II) intel(0): 360030e4100000180000000f00000000 [ 55.275074] (II) intel(0): 00000000000000000020000000fe0041 [ 55.275087] (II) intel(0): 554f0a202020202020202020000000fe [ 55.275099] (II) intel(0): 004231353058473032205634200a0000 [ 55.275108] (II) intel(0): EDID vendor "AUO", prod id 9297 [ 55.275123] (II) intel(0): Using hsync ranges from config file [ 55.275131] (II) intel(0): Using vrefresh ranges from config file [ 55.275140] (II) intel(0): Printing DDC gathered Modelines: [ 55.275150] (II) intel(0): Modeline "1024x768"x0.0 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync (48.4 kHz) [ 55.275180] (II) intel(0): EDID vendor "AUO", prod id 9297 [ 55.275297] (II) intel(0): Not using default mode "1152x864" (width too large for virtual size) [ 55.275308] (II) intel(0): Not using default mode "1280x960" (width too large for virtual size) [ 55.275317] (II) intel(0): Not using default mode "1280x960" (width too large for virtual size) [ 55.275325] (II) intel(0): Not using default mode "1280x1024" (width too large for virtual size) [ 55.275333] (II) intel(0): Not using default mode "1280x1024" (width too large for virtual size) [ 55.275342] (II) intel(0): Not using default mode "1280x1024" (width too large for virtual size) [ 55.275350] (II) intel(0): Not using default mode "1600x1200" (height too large for virtual size) [ 55.275359] (II) intel(0): Not using default mode "1600x1200" (height too large for virtual size) [ 55.275367] (II) intel(0): Not using default mode "1600x1200" (height too large for virtual size) [ 55.275375] (II) intel(0): Not using default mode "1600x1200" (height too large for virtual size) [ 55.275384] (II) intel(0): Not using default mode "1600x1200" (height too large for virtual size) [ 55.275392] (II) intel(0): Not using default mode "1792x1344" (height too large for virtual size) [ 55.275400] (II) intel(0): Not using default mode "1792x1344" (height too large for virtual size) [ 55.275409] (II) intel(0): Not using default mode "1856x1392" (height too large for virtual size) [ 55.275417] (II) intel(0): Not using default mode "1856x1392" (height too large for virtual size) [ 55.275425] (II) intel(0): Not using default mode "1920x1440" (height too large for virtual size) [ 55.275434] (II) intel(0): Not using default mode "1920x1440" (height too large for virtual size) [ 55.275442] (II) intel(0): Not using default mode "1152x864" (width too large for virtual size) [ 55.275450] (II) intel(0): Not using default mode "1152x864" (width too large for virtual size) [ 55.275459] (II) intel(0): Not using default mode "1152x864" (width too large for virtual size) [ 55.275467] (II) intel(0): Not using default mode "1152x864" (width too large for virtual size) [ 55.275475] (II) intel(0): Not using default mode "1152x864" (width too large for virtual size) [ 55.275484] (II) intel(0): Not using default mode "1152x864" (width too large for virtual size) [ 55.275492] (II) intel(0): Not using default mode "1360x768" (width too large for virtual size) [ 55.275501] (II) intel(0): Not using default mode "1360x768" (width too large for virtual size) [ 55.275509] (II) intel(0): Not using default mode "1400x1050" (height too large for virtual size) [ 55.275517] (II) intel(0): Not using default mode "1400x1050" (height too large for virtual size) [ 55.275526] (II) intel(0): Not using default mode "1400x1050" (height too large for virtual size) [ 55.275534] (II) intel(0): Not using default mode "1400x1050" (height too large for virtual size) [ 55.275554] (II) intel(0): Not using default mode "1440x900" (width too large for virtual size) [ 55.275563] (II) intel(0): Not using default mode "1600x1024" (width too large for virtual size) [ 55.275571] (II) intel(0): Not using default mode "1680x1050" (height too large for virtual size) [ 55.275580] (II) intel(0): Not using default mode "1680x1050" (height too large for virtual size) [ 55.275588] (II) intel(0): Not using default mode "1680x1050" (height too large for virtual size) [ 55.275596] (II) intel(0): Not using default mode "1680x1050" (height too large for virtual size) [ 55.275604] (II) intel(0): Not using default mode "1680x1050" (height too large for virtual size) [ 55.275612] (II) intel(0): Not using default mode "1920x1080" (height too large for virtual size) [ 55.275620] (II) intel(0): Not using default mode "1920x1200" (height too large for virtual size) [ 55.275628] (II) intel(0): Not using default mode "1920x1440" (height too large for virtual size) [ 55.275636] (II) intel(0): Not using default mode "2048x1536" (height too large for virtual size) [ 55.275644] (II) intel(0): Not using default mode "2048x1536" (height too large for virtual size) [ 55.275652] (II) intel(0): Not using default mode "2048x1536" (height too large for virtual size) [ 55.275664] (II) intel(0): Printing probed modes for output LVDS [ 55.275676] (II) intel(0): Modeline "1024x768"x60.0 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync (48.4 kHz) [ 55.275694] (II) intel(0): Modeline "1024x768"x85.0 94.50 1024 1072 1168 1376 768 769 772 808 +hsync +vsync (68.7 kHz) [ 55.275711] (II) intel(0): Modeline "1024x768"x75.0 78.75 1024 1040 1136 1312 768 769 772 800 +hsync +vsync (60.0 kHz) [ 55.275727] (II) intel(0): Modeline "1024x768"x70.1 75.00 1024 1048 1184 1328 768 771 777 806 -hsync -vsync (56.5 kHz) [ 55.275744] (II) intel(0): Modeline "1024x768"x60.0 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync (48.4 kHz) [ 55.275760] (II) intel(0): Modeline "832x624"x74.6 57.28 832 864 928 1152 624 625 628 667 -hsync -vsync (49.7 kHz) [ 55.275777] (II) intel(0): Modeline "800x600"x85.1 56.30 800 832 896 1048 600 601 604 631 +hsync +vsync (53.7 kHz) [ 55.275793] (II) intel(0): Modeline "800x600"x72.2 50.00 800 856 976 1040 600 637 643 666 +hsync +vsync (48.1 kHz) [ 55.275808] (II) intel(0): Modeline "800x600"x75.0 49.50 800 816 896 1056 600 601 604 625 +hsync +vsync (46.9 kHz) [ 55.275824] (II) intel(0): Modeline "800x600"x60.3 40.00 800 840 968 1056 600 601 605 628 +hsync +vsync (37.9 kHz) [ 55.275839] (II) intel(0): Modeline "800x600"x56.2 36.00 800 824 896 1024 600 601 603 625 +hsync +vsync (35.2 kHz) [ 55.275855] (II) intel(0): Modeline "640x480"x85.0 36.00 640 696 752 832 480 481 484 509 -hsync -vsync (43.3 kHz) [ 55.275871] (II) intel(0): Modeline "640x480"x72.8 31.50 640 664 704 832 480 489 492 520 -hsync -vsync (37.9 kHz) [ 55.275887] (II) intel(0): Modeline "640x480"x75.0 31.50 640 656 720 840 480 481 484 500 -hsync -vsync (37.5 kHz) [ 55.275902] (II) intel(0): Modeline "640x480"x59.9 25.18 640 656 752 800 480 490 492 525 -hsync -vsync (31.5 kHz) [ 55.275918] (II) intel(0): Modeline "720x400"x85.0 35.50 720 756 828 936 400 401 404 446 -hsync +vsync (37.9 kHz) [ 55.275933] (II) intel(0): Modeline "640x400"x85.1 31.50 640 672 736 832 400 401 404 445 -hsync +vsync (37.9 kHz) [ 55.275949] (II) intel(0): Modeline "640x350"x85.1 31.50 640 672 736 832 350 382 385 445 +hsync -vsync (37.9 kHz) [ 55.600586] (II) intel(0): EDID for output TV for many-many times. I attach you Xorg.0.log recorded during one startup where my problem appeared. More info: This thing looks like part of my screen appearing in random place for a tiny moment. And it usually happens either when computer is idle (with any programs opened) or with specific programs (like QDevelop). Please help, this problem makes once computer nearly useless.