If you recently upgraded to a new MAC there is a good chance it is an Intel based system. It is likely you were on an older model that did not use Intel processors. There is a VPN client made specifically for your new machine and you will need it if it is going to work properly.
First, go to your finder window and locate the Applications folder. Find the VPN client and drag it into the trash. Also do this with the icon located in your dock.
Then go the Blink website to this address: http://blink.ucsd.edu/Blink/External/Topics/How_To/0,1260,24405,00.html
Click the Download link in step 2 of the How-to and then proceed to follow the directions from there. When it asks you for a username and password from within the VPN Client, provide your ACT appointed network username and password. All other password requests are your computer password to allow the install.