Hello James, 

Are you accessing WEBENCH from ti.com or from a bookmarked link?  I am not seeing any problem with access:

Start from the home page, click Design resources, you get to: https://www.ti.com/design-resources/design-tools-simulation/webench-power-designer.html 

then click WEBENCH which should take you to this page: https://www.ti.com/design-resources/design-tools-simulation/webench-power-designer.html .

Also try clearing cache/cookies.

~Leonard