Vista double monitor display issue ~ Offset dropdown menus

[Egg Bramhill]

I purchased a new Dell computer about a month ago and I use it with a double monitor display. Ever since I set it up I've had problems with miss-aligned menus, but until now have been too busy to track the cause down.

The problem is that when I hover or select a menu item with a drop-down menu the drop-down menu is often miss-aligned. What's worse is the shoot-out sub menus often shoot-out the wrong way (left instead of right) even though there's ample screen room.

Here's a couple of screen grabs showing these problems.

In SS1 you can see that the FILE drop-down menu is offset from the FILE main menu button.

In SS2 I've moved the window across the screen towards the right. Now the FILE drop-down menu appears to the left but the shoot-out menus appear to the left although there's adequate space for them to appear to the right!

Finally in SS3 you can see that if I right click over a blank area of screen I get the menu item ATI CATALYST(R) sub menu. If I click on this nowt happens.

Anyone any ideas?