If you're computer has Bluebeam installed, see "On a Computer that uses Bluebeam" down below.
If Internet Explorer is attempting to download files in the portal instead of viewing them, configure your machine with Adobe Reader Version 10 (link). If you have a different version of Adobe Reader installed, uninstall it and install Version 10.
Restart Internet Explorer. You should be able to view PDF's in Internet Explorer now without downloading them.
On a computer that uses BlueBeam:
If Bluebeam is downloading Earnings instead of viewing them in the browser:
1) Open Bluebeam Administrator from the start menu
2) Navigate to the last tab titled "Revu"
3) Check "Display PDF in Internet Explorer"
4) Click Apply followed by Ok.
5) If Internet Explorer is already open, restart it.