macbook air rejecting correct wifi password

I recently moved and have set up a new wifi network. Everything has been fine, but after a few weeks, my macbook starting rejecting my correct wifi password. The network is remembered in my keychain, but if the computer is closed or goes to sleep most times now it wont be able to connect automatically, so I select it from the wifi dropdown. I enter the correct password and it says the password is incorrect. I'll literally leave the same password in (not even retype it) and after 5 or 6 tries, it accepts it. Sometimes it might reject it 10 times in a row, and i'll restart and then it eventually accepts it. I'm not having any problems with any other devices so I think it is this computer. Any suggestions?