Hello zimbrich and thanks for contacting us.

I have no idea why Outlook.com doesn't work under Firefox on XP.

You may try to run Firefox in Safe Mode so no extension that modifies Firefox inner working is opened. Try the Firefox Safe Mode to see how it works there. The Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open the Firefox 4.0+ Safe Mode by holding the Shift key when you use the Firefox desktop or Start menu shortcut.
• Or use the Help menu item and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Don't select anything right now, just use "Continue in Safe Mode." To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut (without the Shift key) to open it again. If it is good in the Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one.

Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

If that doesn't work, maybe there are some cookies damaging your experience. Many site issues can be caused by corrupt cookies or cache. In order to try to fix these problems, the first step is to clear both cookies and the cache. Note: This will temporarily log you out of all sites you're logged in to. To clear cache and cookies do the following:

1. Go to Firefox > History > Clear recent history or (if no Firefox button is shown) go to Tools > Clear recent history.
2. Under "Time range to clear", select "Everything".
3. Now, click the arrow next to Details to toggle the Details list active.
4. From the details list, check Cache and Cookies and uncheck everything else.
5. Now click the Clear now button.

Further information can be found in the Clear your cache, history and other personal information in Firefox article.

If that doesn't work too, you may try Firefox Portable , a Firefox build that doesn't depend on any file or setting you have on your computer so you can check if the issue is on your computer or on Firefox browser in general.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

I believe it may have been virus related. I put a new 500GB HDD in my Wife's PC and loaded Windows 7 Pro x32. Everything is working great and much faster, as expected! I downloaded Microsoft Security Essentials and ran a full scan, including the old HDD which I had connected via a USB-to-SATA adapter and it found a trojan on the old HDD. It then removed the virus and I proceeded to transfer all of her files from the old PC HDD to the new HDD.

I think I will run a full scan one more time tonight, but so far, so good! DZ

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try some of the following programs to scan for malware:

• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Microsoft Security Essentials (A good permanent anti-virus if you don't already have one)

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

I have an older version of firefox, fresh from a system reinstall. The outlook.com website is displaying as a mobile WAP site, displaying all the action links with a corresponding number key for keypad navigation. Looks like MS is discriminating against FF again. Works fine in Chrome...

That is not possible. I'm using Firefox 15.0.1 under Windows 8 RTM and Outlook.com works as expected.

Check your user agent on about:config and also update Firefox to the latest version.

OK. Seems fixed in 15.0.1 after updating

Maybe it wasn't fixed, maybe just you had an old Firefox build.

We're glad it seems you fixed your issue. Next time you should remember to check you have done all troubleshooting steps such as Safe Mode, Reset Firefox, updating Firefox, getting crash IDs and clearing cookies and cache so we can help you faster withouth having to tell you try these things and waiting before you do them. If you perform any step, always remember to type it on your question so we know you did.

Here you can see some useful Troubleshooting articles.

• Websites don't load - troubleshoot and fix error messages
• Troubleshoot Firefox issues using Safe Mode
• Reset Firefox – easily fix most problems
• Remove recent browsing, search and download history
• Update Firefox to the latest version
• Latest Firefox issues
• Firefox crashes - Troubleshoot, prevent and get help fixing crashes

I'm using FF ESR 10.0.7. It doesn't work correctly on outlook.com. I can sign in but not send mail. Outlook page says all FF versions since 10 work. Replicated this on 2 computers, one Vista, one XP. Portable apps FF v 15 does work correctly. Do you know any reason the ESR might not work? I noted a comment about about the user agent, realize it might be something like that, but I don't know how to change it. Thanks.

I was having a similar problem w/ Outlook.com on my work laptop running WinXP & Firefox v16.0.2.

Just spent my lunch break running through the suggestions listed above, and nothing worked, so I opted to try creating a new test profile. Logging in using it, Outlook.com displayed correctly. So using the new profile, I systematically went through and replaced new files w/ the old ones until I found the point that Outlook.com stopped displaying correctly. Turns out that there were two files that seemed to be involved in causing the issue: prefs.js & users.js.

Based on what I have read, there must have been a preference saved in the prefs.js file that was causing the Outlook page to display incorrectly. By simply replacing the prefs.js file in my old profile, w/ a clean one from the new test profile, and removing the users.js file, I seem to have resolved the issue.