I have an internship in a corporation and am trying to get my MBP on thier network. It is an open Guest network with just a user ID and password through a portal, not for the server. My macbook (OS X 10.6.8) Has taken me to this login portal 2 times in 3 weeks. Day 1, which I did not have a login at that point, and Friday after clearing my NVRAM. Every other time, including today, it takes me to an Invalid Server Certificate screen. I have cleared the NVRAM again, cleared my internetconfig files in my preferences and have renewed the DHCP lease. (Not sure if the DHCP renewal was necissary or what it does). I can access the login page 100% of the time from my cell and all PC laptops around me access this also. I am assuming that my MBP is retaining some setting or recognision of the network and it is throwing me to the Invalid Server hell page. P.S. I have tried tech support but they said they have given me the login to their open network and since the computer is my personal, I am on my own. Thanks.