I can’t open email attachments of any kind. I use both Firefox and IE (latest versions), and have the same issue with both.

 I can't open email attachments of any kind. I use both Firefox and IE (latest versions), and have the same issue with both. My preference is Firefox, and the Firefox support site's suggestions don't work. Anyone know how to fix this?

I've gone through many suggested steps already with no success - rebooting, disabling add-ons, clearing cache/temp files/etc., running in "safe mode."

when i go to open them it says certificate error

Please help.