[CrackBerry Question]

I live in Shanghai and I'm using a friend's second hand blackberry as my old phone was stolen. Totally new to the blackberry world but I've quite enjoyed it for almost 2 months until now. I did the update yesterday and now I keep getting the error "The SIM card is from an unknown source". Trying to get a hold of my friend but he's in the USA. Any help would be appreciated. I'm also frustrated by the slow reboot of my phone each time I restart it (up to 10 minutes!) and the fact that WeChat (or WeiXin) is taking 2-3 minutes to open, as well as other apps. It's about 30 seconds for my settings to open.