mattglick93 on "Internal Server Error"

HI,
Anytime I install a plugin, when I activate it, an "Internal Server Error' page appears, and locks me out of my entire site! I tried downloading directly, and also downloading to my computer and then uploading to the site, but neither work. The only way to fix the problem is to delete the plugin files. Latest plugin I tried was the "The Google + Plugin'. Not sure what is causing this, any help would be appreciated!