Hey Guys

I bought my n900 around four months ago, and everything was perfect then. Recently i,ve noticed that when i press the bottom middle section of touchscreen, it gives a creak sound. Tough sound is not much audible, you can feel the 'creak'. it can be very irritating sometimes, although the touch screen works perfectly there and i have also performed a dead pixel test. Sometimes the creak is loud sometimes its not very loud.

So any ideas how to solve this problem, maybe by tightening the screws or something like that. Thanx in advance