I find it interesting sad when websites have pretty old browser requirements. Here are the requirements for logging into XM Radio's account login
Minimum Browser Requirement:
Cookies are enabled
Microsoft Internet Explorer - Version 5.01 and higher
Netscape Navigator - Version 4.x and higher
AOL - Version 7 and higher
The problem here is that they don't recognize Firefox 18.104.22.168 as newer than Netscape Navigor 4.