because your mic/ground contacts is probably bent and shorting out see picture if you open it up you might be able to bend it back, i don't know. here's an example of how someone bent it on another phone sorry, i can't find one for n900, maybe these are the same though: http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=130432573561 http://cgi.ebay.co.uk/GENUINE-NOKIA-...item1c13c747d3 http://cgi.ebay.co.uk/GENUINE-NOKIA-...item19bd89c528