Help Desire Z shuts itself off - several times a day - what could it be?

[norweger]

My HTC Desire Z has begin shutting down, especially when I flip in the keyboard. Any ideas as to what can be causing it? (I'm guessing hardware, but I've had some apps do strange things in the past).

Any ideas as to how to fix it?

 

[norweger]

It works fine for now. Seems like it was some problems with the battery. Now that I've jiggled it a little, it hasn't shut of for a day.