That is really odd. I'm able to go into the website and click right on the flag and make the changes without problem. Are you using a bookmarked link by chance? As an initial suggestion, I would completely clear the cache and cookies on your browser. On a PC, you can hold "Control - Shift - Delete" within any browser to clear these; deleting the bookmark before hand if you're using one. If you're on a Mac, it's a slightly different process, so you can use the article below if need be:
I hope this helps!!
I've had the Slingbox 500 for the past 2 years & it has worked fine between my time in Canada & the US. I recently moved houses in Canada & had to reset the Slingbox. After the reset, my computer shows my country as US - top right corner - in the past, I could double-click on that & the page showing the various country options would appear & I would click on "Canada-English" - it now won't respond to the double-click - nor will allow me to go on the Web Player where I could change it under Settings - Any ideas?