[nkuza]

Is it possible that the battery is loose and not making proper contact? This was an issue on some of the older devices. People would fold a business card in half and insert it before putting the battery door on.

http://forums.crackberry.com/showthread.php?t=663197

Thanks for the link... Pity that I already sent mine back, otherwise I would have tried this. But come to think of it mine started after a day of installing whatsapp. Will have to wait for the warranty assessment.

[southlander]

I do have Whatsapp, my P'9881 runs perfectly and surprisingly now the phone rebooted only ONCE!

You should have zero unintentional reboots on a properly working device. Unless you drop it on the floor hard or something.

[albee 1]

If it works for that long without rebooting after a fresh install it is self inflicted. Its something you are doing or downloading.