Interactive map site won't work

We have two Dell Precision workstations that were purchased at the same time, identical configurations, that won't display this following site correctly.

http://www.assessor.saccounty.net/accessibility/gis-accessibility-disclaimer.html
Click "Accept" at the bottom to get the map to open up.

On one machine, the map area is blank white, and the other it shows an intial image but it's dead, no interactivity. Basically all the other dells we have can do it, newer and older computers. IE is up to date. XP, SP2.
Identical IE version to a computer that does work right.

According to geoprise.net, the company that makes the site, the client side is largely javascript.

Any ideas?