I'm using an older laptop now that has Thunderbird installed. When I
powered up the program this morning, Thunderbird updated to the most
recent version and now, when I try to send an email, it's telling me I
have a "invalid certificate" or "same certificate" and rejects the
email from being sent.

I've spent the last hour trying to figure it out, but I can't find any
information on this. I never needed it before, now I do. It's the
same server I've used for years. The other odd thing is that my main
computer upgraded T-bird fine with no problems.

Any hints?

I'm using the portable because I'm officially crippled - seriously.
Short term, but crippled. :)

I'd appreciate any thoughts on it.