MacBook Air ultra sensitive

Question

I mostly use my new MacBook Air 4,2 (1.7 GHz Intel Core i5 running OS 10.7.2) in the office using a remote keyboard and monitor.  In the evening I use it at home, perched on my lap. In the office it works flawlessly.  At home, it has become increasingly temperamental. 
When I am working in a document, while using it as a laptop, things go fine as long as I'm just typing away.  When I need to go back in the document and click, e.g. to make a correction, it comes up with a contextual menu e.g. Cut Copy Paste, etc.  These menus come up when I'm in Finder, Safari, in fact anywhere I click.
It is particularly frustrating in Excel where there typically is a lot of clicking in cells. Repeated clicking will make the menu go away and the cursor will appear again. The next few clicks are fine and then the problem returns. While typing this, I clicked on the header (Start New Discussion: Apple Support Communities), a menu appeared: Hide Toolbar, Customize Toolbar. When I click again, the same happens, next click, it is gone.
I thought it had something to do with positioning but I have not found a position where the machine works reliably. I am writing this with a heavy book under it, on my lap.  I have tried to squeeze and bend the case to find a physical reason, without avail.  I thought it might have been fitted with a Sudden Motion Sensor but, in the absence of a hard disk, there is no reason for one. Of course, the System Profile does not show it fitted.
Has anyone struck this problem before or can anyone suggest a way to narrow down the problem?

Answer 1

1. System Preferences > Accessibility > Mouse & Trackpad
     Double-click speed
    Try adjusting the speed a bit lower.
2. Shutdown the computer.
    Clean the Trackpad with a dry microfiber cloth.