Seems to be part of general driver problems. See thread: http://en.community.dell.com/support-forums/laptop/f/3518/t/19477666.aspx

The same is happening to me; touchpad becomes unresponsive, inconsistently. Doesn't seem to be related to processor load.

Happens to mine all the time as well, worse after the update to the A04 cypress driver.  Honestly, I love my XPS12, but this is frustrating enough that I have moments I'd like to pitch it at this point.

That's unfortunate, the A04 (late jan) version seems to have fixed it for me.  Have you tried uninstalling/re-installing / rebooting?  I am reaalllly hoping the problem which was intermittent to begin with doesn't return for me.  I do find that if I hold a key down, the trackpad doesn't respond.

Removed the touchpad driver, updated BIOS to the A05 bios, and reinstalled the A04 driver.  I had missed the available BIOS update before.  Since doing both updates, I have not yet had further problem.

I too have the issue.

A05 Bios

Cypress Track Pad Driver 2.5.1.42 (21/12/2012)

Interestingly my touchscreen has similar issues i.e. it freezes for a few seconds becoming unresponsive and then randomly active again about 10-20 seconds later. The same behaviour as the track pad. Feels like a BIOS\Driver issue... anyone have any update on these problems? Seems quite common.

I have the same problem, can you kindly direct me to the relevant drivers thank you

I'm still having this problem as well ;(