Firefox says "sec_error_unknown_issue" for this forum

I cannot open this forum by Firefox 38.0.5. It shows “Error code: sec_error_unknown_issue”.
Site cirtification looks invalid. IE 11.0.96 works OK though.
Is it me only? If not, I think Comodo forum owner should take appropriate action.

Refer to this . A step further would be to run the Command Prompt as administrator and enter --------> Dism /Online /Cleanup-Image /RestoreHealth. Most likely not the problem but you never know. also maybe this .

good luck .

Thanks!, sAyer, problem resolved.
The first linked site was not my case, but, in it was the suggestion of creating another account in Firefox.
Making new account could enable to put Comodo forum as exception of certification error.

(I had to transfer all bookmarks, cookie settings, and add-ons from old profile, though.)
Tanks again, Tak