I'm not sure if this is linked to XP, but since it persists beyond my browser, I'll have to assume it does.
Sometimes, seemingly randomly, when I'm typing, my keyboard suddenly changes modes. Instead of typing out letters, the keys activate different statusbar and toolbar menus and windows, like opening the File dropdown and whatnot. When this happens, the scroll on my mouse changes modes too - instead of moving up and down a page, it's like pressing Back and Forward. And I cannot change windows without closing previous ones, because they stay in front.
Being so reliant on a keyboard, this makes my computer practically unusable during a session, and I have to manually turn off the power and reboot to use it again. It even happens with the On-Screen Keyboard. I'm sure I'm not pressing any special/wrong keys - it seems completely random, other than seeming to occur more often in a space of a few hours.
I've virus scanned. Nothing there either. What's wrong?