I just fixed an annoying problem on my old Toshiba Tablet PC - the pen stopped working. To be precise, when I tried to use it the mouse pointer would flicker madly along the top and left edges of the screen, totally unable to track the real position of the pen. And the issue is apparently that a fresh install of XP SP2 disabled "Display Stretch" in the BIOS.

display stretch"Display Stretch" is of course the ugly hack that turns a perfectly readable 640x480 boot screen in the middle of your 1024x768 LCD into a blotchy mis-scaled mess that fills the entire display, and makes you wonder just who thought this would make a good impression on someone booting the laptop for the first time. But it turns out to be vitally important for the peaceful interaction of the Toshiba's digitizer and its Trident CyberBlade video chipset - turn it off and all hell breaks loose, penwise. Knowing this, and assuming that you've got driver version 6.4229.22ICD_Rotation_SE_DXVA_TABLET or later, just open Display Properties\Settings\Advanced\Flat Panel, and check the "Display Stretch" box. Voila!

Big kudos to whoever it was in Microsoft tech support who first tracked this one down and wrote up the solution…