Help Screen not registering input correctly

[hoopr]

Android 2.2
Not rooted
On Vodafone

95% of the time the phone is OK, however occasionally (and for no obvious reason) it starts responding very randomly to user input: not registering input, activating items that have not been selected and other random activity.

I installed a basic drawing app to see exactly what the screen was up to during these episodes... check it out here:

Crazy Phone on Vimeo

The phone has been back for repair once. Factory restore carried out and nothing was identified as wrong, but the problem keeps on happening... any ideas what's going on here?

Thanks

 

[SUroot]

Dodgy digitiser perhaps. It can lead to that sort of thing. Its the glass panel that has a digitising layer, which sits over the screen. Probably needs replacing.