HTTP 501/HTTP 505 Error

I hope this is the correct forum for this problem.  I keep getting this error everytime I try to get into the www.vermont.gov or any sub-sites to vermont.gov:

The website is unable to display the webpage

This error (HTTP 501 Not Implemented or HTTP 505 Version Not Supported) means that the website you are visiting doesn't currently have the ability to display the webpage, or support the HTTP version used to request the page.

I have tried going into the Internet Options, Advanced Tab and removing the checks on "Show friendly HTTP error messages", "Use HTTP 1.1", and "Use HTTP 1.1 through proxy connections".  This was suggested on the Microsoft Support website.  It didn't help. 

Has anyone out there had a problem like this and if so, how did you fix it, short of purchasing a Registry Repair program?
                                   thanks

[Moderator]

What Browser ?

IE 7.  I had tried IE 8 but it didn't play well with Hughesnet.  I should add that this is a website that I had been able to get into in the past.  Thanks....

Registry repair programs would not help.  You DEFINITELY need the HTTP 1.1 checkboxes ticked.

Can you try browsing these sites with a difference browser, say Firefox?  Try temporarily disabling any internet security suite and any add-ons installed in IE (or start IE in "No add-ons" mode).

This is really going to sound weird, but I just tried "one more time" to get into www.vermont.gov and it worked!  For weeks and weeks I've had no luck getting into that site.  The same thing had happened to me about 6 months ago when I was trying to get into www.usa.gov.  Couldn't get into ANY government site.  It seems strange that the only sites I've ever had problems with have been state and U.S. government sites?  I would still like to know WHY this is happening, but, I suppose it is just one of those "fourth dimension" anomalies.
Thanks for your input, Rob.  It is sincerely appreciated. 

Hmm - might be worth posting in the malware forums and going through the virus checking routines...  Glad it's working, anyway.