I've just spent the past few days working a wifi connectivity problem after installing Parallels. Background: Macbook Pro, late 2008 model running Yosemite 10.10.3. Problem: No wifi connectivity issues prior to installing Parallels. None, zip, zero, nada. Good wifi connectivity with non-encrypted communications such as printers, ping, traceroute, etc. NO wifi connectivity with anything that required encryption, such as https. Re-installation of the OS did NOT resolve the problem. Resetting the NVRAM did NOT resolve the problem. After a lot of troubleshooting, I nailed the issue down to invalid SSL certificates. Resolution: More troubleshooting and I nailed it down to Parallels somehow screwing with the system clock during installation such that was slightly wrong, causing SSL certificate errors. I went into Time & Date Preferences and disabled then re-enabled the "Set Time & Date Automatically" setting and my connectivity problems went away. I hope this saves somebody else the days of frustration I just experienced.
