On a freshly built machine (Windows 7 x64 Enterprise) Internet Explorer would not open. If I brought up task manager, I could see the iexplore.exe process start and run briefly, but close without ever opening an IE Window.
Resetting the Internet Explorer settings fixed this issue:
Open the Control Panel, in the upper right change the view to small icons.
Click Internet Options.
On the Advanced tab, click the Reset button, click Reset in the Reset Internet Explorer Settings dialog box, and then click Close.
Retry IE and see if it works now.