k10d sudden overexposure problem

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

How is your camera's metering set up?

Take the lens off and check that the aperture is moving freely and not stuck wide open :
Just move the little acuator on the rear of the lens back and forward and see if the aperture is opening and closing freely.

You might have inadvertently moved the metering mode to "spot metering" and been pointing the camera to a bright part of the scene while shooting!!! Another thing that could happen is "locking" exposure with AF point. Depending on the subject and AF point, it can seriously "screw up" your exposure. Just a wild guess...

Unfortunately you've removed the EXIF information on your uploaded shots.

I would also guess that you've flicked the metering mode to centre or spot. It's caught me out before
Opening the original JPG/PEF/DNG in Pentax Browser will show you what metering mode you used for these shots.

The other way of telling is to take a shot of a very evenly lit wall. My guess is that would be exposed correctly (remembering that it's metered to around 18%).

Hope that helps you find the problem!
Matt

Thanks for your thoughts. The metering is on pattern, if you click on more properties to the right of the photo you should get all the exif info. The problem occurs on all metering modes and ae lock isn't being activated. Unfortunately the effect is apparent on every subject I photograph, always about +2ev. I've been unable to check the aperture on the lens by depressing the lever because I'm at work, but I will have a look as soon as I get home.
Thanks again, I fear it may need a trip to the engineer.

jim

Flickr does that. You can get abbreviated EXIF data from the "More properties" link for each photo. Shows Metering Mode: Pattern.

You might have accidentally dialled in +2ev compensation. Press the +/- button on the back of the camera and check that the top plate LCD shows 0.