Upon a recent reinstall of Vista on a Toshiba Satellite lap top, with all updates other than Sp1 or Sp2---as well as having installed Norton 360 4.0 and then removed it possibly causing the following problems:  No matter what desktop icon I click on to open up a program, the lowest icon or last icon will be highlighted and that software opens up instead. For instance, if Windows update icon, or any other---is the last in a row, or the lowest at the bottom of the desktop---no matter what icon I click on before or above the Windows update icon---will open up instead.  Changing the position of the icons, as well as align to grid etc---does nothing.  If I open the start menu, once I click on any program to open it--highlights the last program listed and opens that instead.   Now for the other asinine occurrence:  Upon opening a web page---no matter what it is---the scroll bar will snap to the bottom so that it is impossible to see what is at the top of the web page.  Trying to drag the scroll bar up will not work, nor will repeatedly pressing the arrows.  The scroll wheel on the mouse does no thing either.  Nothing wrong with the mouse, which works perfectly in XP and 7.   Any thoughts and advice on how to solve this madness will be greatly appreciated.

Wheel is stuck in scroll-down mode. USB mouse? Add a second USB mouse to the system. The first mouse will probably still cause scroll down to be stuck on. Uninstall (in Device Manager?) the first mouse and reboot. If needed try again with PS/2 mouse and with as many mice and ports as possible. Avoid hubs. Once you get a working combo, uninstall all extra mice, reboot, then reinstall original (or preferred) mouse.

You were right jumper!   Not having any other mice to do what you said, I spun the scroll wheel to where it positioned web pages at the top whilst the mouse was hooked up to xp---then taped it with electric tape in that position!  I cannot understand how it works on XP and 7 the way it should, but not on Vista!  Everything works now--but I assume I will need a new mouse for the Vista PC.

What is the make and model of your mouse?

There is no "top" position on the wheel, only up and down directions. The wheel is also a button, so you may now have the button taped "down". In Vista, untape the wheel, click it a few times and retest. You may need a better mouse driver (or to reinstall the current one).

Google "download mouse test tool" for more help.

Well, the problem is somewhat fixed.  I've discovered, that all I have to do, is press the bracket stub (the keypad is missing) next to the P key, and the problem goes away until I start the computer again.  Odd.

The switch under the keycap might have been damaged when the keycap got knocked off. Do you have a spare keyboard to try?

It is a laptop using an external keyboard. And, the key I described is on the laptop, not the external keyboard. If I could de-activate the onboard keyboard, that might reveal something? The next time I go online using that laptop which is not what I am using now, I will hit the bracket key on the external keyboard and see if it resolves the problem.