Have a mid 2009 macbook pro 15inch. Lately I've been getting a wifi no hardware installed problem, my mac was also constantly jamming needing to force restart. I re-formatted it and re-installed Mountain Lion, however now the wifi symbol does not even shot up at the top, and sometimes after a shut down it and re-switch on, it may connect to wifi, however it will jam after a while - maybe 5 minutes and force me to switch off from power button. When I would switch it back on it will start from scratch with no Wifi. Warranty is finished and in Malta there isnt a quick/cheap service, so would appreciate any feedback as I've been around a month with this problem, and am forced to use ethernet, however this is extremely inconvenient as I switch off wifi for everyone else to use internet.