Why do I only have temporary access to the internet?

1)  You do not have a proper anti-virus (more information at Anti-Viruses for Students)

2)  You do not have all Microsoft updates installed.  To install Microsoft updates go to Start, then to Control Panel, then to Security Center.  From here "Check for the latest updates from Windows Update." 

3)  You may be using Google Chrome.  If so you will need to switch to Internet Explorer or Mozilla Firefox.  You can open up the access control page in one of these browsers and do your actual web browsing in Google Chrome but you will need to be in either Internet Explorer or Mozilla Firefox.