Pentax 18-250 and k10d overexposure

I've owned my k10d for a couple of months now and it has been doing a brilliant job until now. Suddenly it has started overexposing all my shots by about +2ev. I've only tested in AV mode and the green mode but I'm assuming the result would be the same in all modes. I only have one lens which is a Pentax 18-250 so I can't tell if it's the camera, the lens or me to blame. Has anyone else seen a similar problem?
I've uploaded a couple of examples to flickr to show you the problem, unfortunately I've just taken these in my dimly lit living room so the overexposure isn't as noticeable as it is on a sunny day, the problem should still be pretty obvious though.
This is the exposure the camera thinks is a good idea.
http://www.flickr.com/photos/33748762@N00/2669267252/
This is with compensation set to -2ev
http://www.flickr.com/photos/33748762@N00/2669265894/
Any Ideas would be gratefully received.
jim

Please don't double post!

Other thread is: https://www.pentaxuser.com/forum/viewtopic.php?t=8535&highlight=

(This one locked!)