Opening PDB from Zhang Server
I previously mentioned having trouble downloading the PDB files from the Zhang Server (I-TASSER). I thought it was just me, until I started getting traffic from users searching for “cannot open PDB file I-TASSER”. The problem ended up being how my Firefox browser was set up on one computer verse another. If you are having this problem – here is how to fix it.
When my browser was not set up correctly, I would get the following displayed when clicking on Download Model2 (for example).

Edit–> Preferences –> Applications

Scroll down until you find the file type PDB then change to Save File then click Close

If you are using an older version of Firefox try the following:
Edit–> Preferences –> Content –> File types Manage