Check the connection settings.

• Tools > Options > Advanced : Network : Connection > Settings
• https://support.mozilla.org/kb/Options+window+-+Advanced+panel

If you do not need to use a proxy to connect to internet then select "No Proxy" if the default "Use the system proxy settings" setting doesn't work.

See "Firefox connection settings":

• https://support.mozilla.org/kb/Firefox+cannot+load+websites+but+other+programs+can

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

I tried that, and now this pops up: An error occurred during a connection to startpage.com.

You have received an invalid certificate. Please contact the server administrator or email correspondent and give them the following information:

Your certificate contains the same serial number as another certificate issued by the certificate authority. Please get a new certificate containing a unique serial number.

(Error code: sec_error_reused_issuer_and_serial)

Have any idea what to do?

I've also noticed that it does try to pop up the search results (and every once in a while will pop them up), but most of the time it just gives me what I listed in the above question.

Does anything come up on the about:config page via the location bar if you enter startpage in the Search bar at the top of the about:config page?

• http://kb.mozillazine.org/about:config

No, nothing.

Who issued the certificate?

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

• Click the link at the bottom of the error page: "I Understand the Risks"
  

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

• Click the "View..." button and inspect the certificate and check who is the issuer.
  

You can see more Details like intermediate certificates that are used in the Details pane.

Do a malware check with some malware scanning programs on the Windows computer.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.microsoft.com/security/scanner/en-us/default.aspx - Microsoft Safety Scanner
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy

You can also do a check for a rootkit infection with TDSSKiller.

• http://support.kaspersky.com/viruses/solutions?qid=208280684

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

I ran all those scans, and found nothing. Also, the certificate page only popped up twice, and when it did, there was no button to click to see the certificate. It just told me what I posted above.

I didn't find out until just now, but it's also doing it on my other computer (and that updated like a week ago).

Did you check who issued that untrusted certificate [*]?

It says it's verified by godaddy.com (I don't really know what I'm looking for), and that everything's been verified.

That looks OK. I see that the certificate is issued by Go Daddy Secure Certification Authority.

Try to rename the cert8.db file in the Firefox profile folder to cert8.db.old or delete the cert8.db file to remove intermediate certificates that Firefox has stored.
If that helped to solve the problem then you can remove the renamed cert8.db.old file.
Otherwise you can rename (or copy) the cert8.db.old file to cert8.db to restore the previous intermediate certificates.
Firefox will automatically store intermediate certificates when you visit websites that send such a certificate.

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder

I tried that, and it still didn't work. But I completely uninstalled firefox on my other computer, and downloaded version 10 (beta 6 I think). When I tried to use the startpage and ixquick search engins, the certificate thing popped up again (this time with the 'get certificate' button you were talking about). When I click get certificate it says No Information Available, Unable to obtain identification status for the given site.

Thanks for all you help, but I think this is just something that'll have to wait until they come up with a new version to fix (if that even works).

Thanks again for all your help!

The startpage.com loads fine for me with a correct certificate chain, so I don't know why it doesn't work for you.

Do you know why that page is even loaded as it is not standard and you may have other software on your computer that has done this.

Create a new profile as a test to check if your current profile is causing the problems.

See "Basic Troubleshooting: Make a new profile":

• https://support.mozilla.org/kb/Basic+Troubleshooting#w_8-make-a-new-profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If the new profile works then you can transfer some files from the old profile to that new profile, but be careful not to copy corrupted files.

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Thanks, but that didn't even help. I don't know what's wrong with it, but I'm just going to wait and see if it will just fix itself (it keeps acting like it's trying to connect, and every once in a blue moon, it will for a second). Google fixed itself after a few days, so I'm hoping the others will start working in a few days too.

Thanks for all your help, it might not have fixed this problem, but with all the info you gave me, I know how to check for other problems know (and the last one fixed another problem).