Enhanced email option not working

"The Tech Support person said there may be an issue with Adobe Shockwave as this is somehow used by Mozilla Firefox to access some browser options or sites."

I believe the site uses flash, although it may use some elements of Shockwave. Try these two links to test both;

http://www.adobe.com/software/flash/about/

https://www.adobe.com/shockwave/welcome/authorwareonly.html

You may also want to delete your temporary flash files. Has the site ever worked since upgrade to Windows 10?

See here for instructions to clear Flash temp files: https://forums.adobe.com/message/4278569

Do you mean Firefox can't run Flash on Windows 10, or can't run Flash in general? Enhanced Webmail is working fine for me with latest Firefox and flash plugin on Windows 7 Pro. See this support article;

https://support.mozilla.org/en-US/questions/1044236 

And when I got to the site without the plugin, it gives me a totally different message then what OP is getting. Could you quote your source?

Firefox runs flash & enhanced webmail fine on my Windows 10 laptop.  I'm not sure why tech support is talking about Shockwave, I don't have it installed and enhanced webmail works without it.

ChrisL said:
Firefox has chosen to block the Flash Player plugin from being usable in their most recent browser versions.

Not quite. The article said Firefox blocked flash's latest plugins after some vulnerabilities were found. They didn't drop support all together. They aren't Apple. Also, the article has been updated that Firefox nows allows it since the latest flash updates have patched the vulnerability;

"UPDATE: Adobe on Tuesday released two updatesto patch the remaining Flash Player vulnerabilities on Windows, Mac, and Linux."

I would suggest OP make sure both Firefox and Flash are up to date and working. See here for Firefox's Flash troubleshooting support section: https://support.mozilla.org/en-US/kb/keep-flash-up-to-date-and-troubleshoot-problems

Followed your suggestions and had absolutely no affect. Thanks for your help though.

Chris, 

   I upgraded from Win 8.1 to 10 on 29 July and began using Mozilla Firefox withing a few days because IE11 was pathetically slow and up until a few days ago had absolutely no problems running Enhanced webmail with Mozilla Firefox.  I also lost my webmail access on my iPad because I had it set up using the Enhanced webmail as well. It took me awhile but I finally managed to get my email back on my iPad using the Classic webmail option. I have also tried accessing Enhanced webmail using Edge, Chrome and the old IE11 and all give me the same results with the "Oops! cannot find that page" message. All DO work using Classic. It was strange because as I stated I opened and read my email about 7:30 AM, closed out of it and came back in about an hour and half later and this is when I began getting the "Oops!" message. I have tried refreshing Mozilla Firefox thinking maybe if there had been some kind of glitch this might fix it....nada. I even did a system restore BEFORE I ever contacted Cox Tech Support. Yeah, I know, I was really clutching at straws there. I have done everything suggested/recommended by the people who have responed to my initial question and I have gotten nowhere. I really do not like the Classic webmail option but I'm slowly getting used to it since I may well be stuck with it. Again, thanks for your help.  

Like I said in my initial question, I was having no problems with Enhanced webmail using Mozilla Firefox up until a few days ago. It was working fine and then less than an hour and a half later it was dead. I clicked on the link you provided but what I got was "Page Not Found". Also, if I am reading your response correctly you are running Windows 7 Pro correct? As I also stated in my initial post I had been running Windows 8.1 using IE11 prior to the Windows 10 upgrade and had no problems at all using Enhanced webmail. Even after I upgraded to Win 10 on 29 July and switched over to Mozilla Firefox several days later (IE11 was S-L-O-W) my Enhanced webmail was working fine until a few days ago. I do appreciate your help. 

I am running version 18.0.0.232 which is much higher than anything shown in the link you provided. It was worth a look though. Thanks.