losing wifi connection and random shut downs
Hi, our 2010 iMac is suddenly frequently losing it's wifi connection. When trying to reinstate the connection, clicking on the wifi icon, it searches for networks but does not see any. This is odd, because like most places there are at least a dozen wifi signals from surrounding buildings. Network repair, doesn't work either. This inevitably leads to random shutdown of the computer that will not respond to pushing the power button, as if it's dead. Only after unplugging and replugging the computer into the socket will it respond to the power button. Doing this fortunately reestablishes the wifi connection but it doesn't last long. I have reset the SMC.
any help appreciated,
Jeff