hello cwestcott, a possible solution depends on different factors:

• what is the error code shown under technical details on the error page?

in case the error code equals sec_error_unknown_issuer, please attempt to add an exception on the bottom of the error page & inspect the certificate (see the screenshot attached for instructions):

• which issuer information does the certificate contain?

thank you!

"This Connection is Untrusted" error message appears - What to do

I already went through all the instructions on the Firefox support forum and nothing worked. The issue can't be the website certificate because it happens for EVERY SINGLE WEBSITE I attempt to access. Regardless, I did add an exception for Facebook per the instructions. That caused a strange, unformatted page to come up. I have since read that to do an exception is dangerous as it can cause MORE unwanted malware to infect the computer.

I did, however, figure it out on my own so maybe this will help people who are experiencing this problem in the future: After reading the past posts from people who experienced the same thing, I realized that in every case, the solution was to remove some sort of unwanted software (malware). I am very careful to NOT download software and I noticed that another victim of this said the same thing so this one is sneaky. I even bought new antivirus software (Norton), ran a scan and the problem was not found.

I went to Programs "uninstall programs," sorted them by date and removed anything that looked suspicious that was recent. I had something with the word, "rocket" in it. It looked like a game. There was also one other program that I removed (can't remember the name of it now). Removing those didn't solve the problem, so I went back through all the programs on my list and removed anything that said "toolbar" on it, even if it sounded trusted (I had a bing and a google toolbar). That didn't seem to work either so I sorted the programs by date again and I noticed that the "rocket" software was STILL THERE.

I right clicked on it and then clicked on "uninstall" again. It takes an exceptionally LONG time for that program to uninstall AND nothing shows up on the screen. The computer just sort of sits there and does nothing. I walked away and when I came back (about an hour later) the program was gone from the list.

Firefox works now. I'm not getting that message anymore, but here's the deal: I am not 100% sure which program was the problem. It was either that rocket software or one of the toolbars. Regardless, the answer always seems to be some sort of unwanted malware so I would recommend that any victim of this problem try uninstalling suspicious programs as a FIRST step. And that means ANY suspicious programs that are RECENT, regardless of whether they look like games or antivirus or whatever. If it's recent and you don't remember downloading it, uninstall it.

I too had the same problem and tried everything the same except the rocket software. Thanks to the above experience I could locate the rocket software, that I had too, and that solved the problem.