No problems here with that link.
The server sends the file with text/html, so it should work.

Try:

• "Clear the Cache": Firefox > Preferences > Advanced > Network > Offline Storage (Cache): "Clear Now"
• "Remove the Cookies" from sites that cause problems: Firefox > Preferences > Privacy > Cookies: "Show Cookies"

cleared cache and all cookies with "dish" in the name. Logged back into dish web site and went to account page https://customersupport.dishnetwork.com/customercare/prepWelcome.do. When I do a view of statement details I still get a message box saying

  you have chosen to open
     viewPastStatement.do
     which is a: do file
     from https://customersupport.dishnetwork.com

 what should FireFox do with this file?

... ...

All the other sections of the https://customersupport.dishnetwork.com/customercare/prepWelcome.do page work.

Tried old statement to see if had anything to do with current dates data but it failed also. I will save the data it is trying to send and try to browse (view) it with vim or something.

Do you have an action for .do files in Firefox > Preferences > Applications ?

See "File handling in Firefox 3 and SeaMonkey 2" and "Reset Download Actions": http://kb.mozillazine.org/File_types_and_download_actions

I have a action for .do - it was always ask. I changed it to use preview(default) but that doesn't work either. I followed the instructions for resetting download actions as follows:

If problems arise or if you want to restore the default set of file download actions, do the following [8]:

  1. Type about:config into the address bar.
  2. Find the preference browser.download.pluginOverrideTypes and, if it is present, right-click on it and select reset.

NONE FOUND

  3. Find the preference plugin.disable_full_page_plugin_for_types and, if it is present, right-click on it and select reset.

NONE FOUND

  4. Open the profile folder. (The profile folder is hidden by default in Windows 7/Vista/XP/2000 and Linux; read this for help finding it).
     Note: In Firefox 3.6 and above you can open the profile folder from the Firefox menu, via "Help -> Troubleshooting Information".

DID THIS BUT WHAT AM I SUPPOSED TO BE LOOKING FOR OR REMOVING?

  5. Completely close your Mozilla browser.

DID THIS

  6. Delete (or rename) the file mimeTypes.rdf. Caution: There is also a mimeTypes.rdf file in the program folder. Do not delete it by mistake. 

DID THIS

NO Change. It fails trying to open preview. (I changed the action) Should there be an action? If not how do I get rid of it? The first lines of the downloaded ".do file" are(as viewed with vim): %PDF-1.3 %âãÏÓ 16 0 obj << /Linearized 1 /L 224745 /H [ 1084 261 ] /O 18 /E 70808 /N 2 /T 224298 >> endobj

"The first lines of the downloaded ".do file" are(as viewed with vim): %PDF-1.3..."

Adobe Reader/Acrobat files (.pdf files) begin with %PDF-#.#; have you tried directing the .do file in your Applications list to open with a PDF reader product, which you do not appear to have installed? The .pdf format is very common for online bill copies, forms, and bank statements.
Download link and more information: https://support.mozilla.com/en-US/kb/Using+the+Adobe+Reader+plugin+with+Firefox#Installing_and_updating_Adobe_Reader

You can also try DishNetwork online chat with Customer Service or Tech Support: http://www.dishnetwork.com/customerservice/contactus/live_chat/default.aspx

You appear to have an out-of-date plugin with known security issues.

• Shockwave Flash 10.0 r45

1. Check your plugin versions: http://www.mozilla.com/en-US/plugincheck/
   • Note: plugin check page does not have information on all plugin versions
2. Update Shockwave Flash
   • Use Firefox to Download and SAVE to your hard drive from one of the links below; the links take you directly to the download and you avoid the "getplus" download manager and "extras" (i.e., toolbars, virus scan links, etc.) on the main Adobe page.
   • SAVE to your Desktop so you can find it

1. • Download links and other information:
     • https://support.mozilla.com/en-US/kb/Managing+the+Flash+plugin#Updating_Flash
     • or you can download, save, then run the manual installers for IE, then for Firefox (and all other browsers) from here: http://kb2.adobe.com/cps/191/tn_19166.html#main_ManualInstaller
   • Also see: http://support.mozilla.com/en-US/kb/Installing+the+Flash+plugin
   • Also see (if needed): http://kb2.adobe.com/cps/191/tn_19166.html#main_Uninstall

installing adobe plugin solved problem.

I am happy that your problem is solved.

Also be sure to update Adobe Flash as I mentioned.

I had this problem with DISH ".do" files both on Mac OSX 10.5.8 and Firefox 3.6.10 as well as Safari 5.0; and IE8 and Firefox on Win 7 in Parallels. No other financial or business site where I have online accounts had this problem - I could either view my statements online or download a PDF that opened in Preview.

I contacted DISH but the support people couldn't figure it out.

Adobe Reader doesn't work with Firefox on Mac according to

http://support.mozilla.com/en-US/kb/using+the+Adobe+Reader+plugin+with+Firefox

so I followed the advice on that page and installed the

PDF Plugin for Firefox on Mac OS X 1.1.3

Now "View DISH statement" works in Firefox.

This drove me nuts. I called Dish and they were clueless. I finally just changed the .do extension to .pdf and it opened right up! (I have Sumatra pdf reader, I don't know if this works with Adobe.)