Here's an odd one that one of my students came across.
He's running the OS X Yosemite and has the latest version of Pd installed. For a long time we couldn't work out why Pd wouldn't work, it just would not open. Then he noticed that when at home it did, but not when he was in Uni.
Here's the odd part, connecting to his open Wi-Fi allows Pd to work, connecting to our network in uni doesn't work, but it does on his mobile phone.
So for the time being, he has to connect to the phones wifi in uni.
Can any one shed any light on this?