Version:           unknown (using 4.1.2 (KDE 4.1.2) "release 45.1", KDE:KDE4:Factory:Desktop / openSUSE_11.0)
Compiler:          gcc
OS:                Linux (x86_64) release 2.6.25.16-0.1-default

I had to downgrade from KDE 4 to KDE 3 in order to continue using my laptop with an external CRT monitor. The problem was introduced, solved and reintroduced in later versions of KDE 4 and makes my CRT monitor switch/probe modes exactly each 10 seconds. The monitor works perfect with KDM but as soon as I start a KDE4 session, each 10 seconds the image goes briefly away, like when the monitor probes a new mode.

The only thing abnormal I can find in the logs are lots of entries like this: 

(II) intel(0): EDID vendor "MAX", prod id 6065
(II) intel(0): EDID vendor "AUO", prod id 12820
(II) intel(0): EDID vendor "MAX", prod id 6065
(II) intel(0): Using hsync ranges from config file
(II) intel(0): Using vrefresh ranges from config file
(II) intel(0): Printing DDC gathered Modelines:
(II) intel(0): Modeline "640x480"x0.0   31.50  640 656 720 840  480 481 484 500 -hsync -vsync (37.5 kHz)
(II) intel(0): Modeline "640x480"x0.0   25.20  640 656 752 800  480 490 492 525 -hsync -vsync (31.5 kHz)
(II) intel(0): Modeline "720x400"x0.0   28.32  720 738 846 900  400 412 414 449 -hsync +vsync (31.5 kHz)
(II) intel(0): Modeline "1280x1024"x0.0  135.00  1280 1296 1440 1688  1024 1025 1028 1066 +hsync +vsync (80.0 kHz)
(II) intel(0): Modeline "1024x768"x0.0   78.80  1024 1040 1136 1312  768 769 772 800 +hsync +vsync (60.1 kHz)
(II) intel(0): Modeline "800x600"x0.0   49.50  800 816 896 1056  600 601 604 625 +hsync +vsync (46.9 kHz)
(II) intel(0): Modeline "1280x1024"x84.8  159.50  1280 1376 1512 1744  1024 1027 1034 1078 -hsync +vsync (91.5 kHz)
(II) intel(0): Modeline "800x600"x84.9   56.75  800 848 928 1056  600 603 607 633 -hsync +vsync (53.7 kHz)
(II) intel(0): Modeline "1024x768"x84.9   94.50  1024 1096 1200 1376  768 771 775 809 -hsync +vsync (68.7 kHz)
(II) intel(0): Modeline "1600x1200"x75.0  204.75  1600 1720 1888 2176  1200 1203 1207 1255 -hsync +vsync (94.1 kHz)
(II) intel(0): Modeline "1024x768"x100.0  112.25  1024 1096 1200 1376  768 771 775 816 -hsync +vsync (81.6 kHz)

in the xorg.log file.

If you need more information, just ask.

Btw. I'm using the opensuse factory builds (x86_64) and my graphic card is an Intel 945GM.