N9 faulty?
 

Hi,

i have problem with my N9 16Gb black. Every few hours,
(its random) nokia start working very slow, then when i try to lock it, clock and notifications are not on the screen anymore. When i unlock it icons looks like in 256 colour mode with many artefacts. Just look same like when PC GPU is faulty and you get a lot errors on screen. I have never noticed any overheating, all soft i installed from ovi store. When i switch off phone, after restart working well again........any idea, please?

many thanks