I bought a factory unlocked Lumia 900 from Amazon and now seeing random reboots every day. I put my phone down and after 10 mins if i check it, the phone is dead. I need to boot that up again. This is completely random. And now nokia is saying that this phone is not having international warranty since this phone was bought in Singapore and sold in USA by manufacturer.
Does anyone know\aware of any fix?
Have you checked this article for basic troubleshooting? http://support.microsoft.com/kb/2749480
An update will be released to fix minor issues with the phone early 2013 but no specific date yet. With regards to the warranty, Nokia does not have international warranty. For full details, check here: http://www.nokia.com/sg-en/support/troubleshooting