Just in case you haven't been there before - right click on My Computer (on desktop icon or start list item), select Properties, select Hardware tab, and click on Device Manager. Sorry if that's obvious!
Quite often there is an "Fn + Key" combination to switch the trackpad on and off. This is, I think, to help proper typist while they are typing. Us "Hunt & Peck" two finger typists don't get the problem.
On my Advent 4211 netbook the "Fn + Key" combination is Fn+F3. The F3 key has a small picture of a trackpad on it in blue.
If you have the Touchpad icon in your Systray (beside the clock), rightclick on the icon and choose "Touchpad Properties". This image should pop up click here Click on the top lefthand icon (Device Select/Button Settings) and this image should appear click here Make sure you click on the "Device Select" tab (arrowed in my image) and the Disable option should be there (also arrowed in my image. Are you seeing those options?