please read this

http://forums11.itrc.hp.com/service/forums/bizsupport/questionanswer.do?admit=109447626+1259686870198+28353475&threadId=147807

Also
Step 1

open the "Control Panel", double click on the "Mouse" icon, then click on the 'Pointer Options' tab, then UNCHECK the box next to "Enhance Pointer Precision

Step 2

1. Click Start > Control Panel > Mouse.

2. From the tabs at the top, choose "Touchpad". Here, you should have a "Tap to Click" tick-box. Remove the tick from this.

If you only have 4 or 5 tabs along the top in this section, try installing the Synaptics touchpad driver from here :

http://www.synaptics.com/support/drive.cfm

Download and install the "Windows Vista 32-bit Edition v10.1.8" driver. Once this has been installed, you should see further options in the mouse properties, and also have the little icon in the system tray. This will then allow you to turn off the tapping function.