Windows 8 'wifi does not have valid ip configuration'

Help! My new laptop which runs windows 8 repeatedly gives me this error message. I've managed to fix it a few times by running the trouble shooter or resetting the adapter but now it won't fix and I have no idea why it keeps doing this - I'm ready to return the machine to the store before I'm stuck with it! Maybe my router is too old? I noticed that when my router shows up it is as an unidentified public network but I can't figure out how to change that.....grrrr!