Thanks Amin....looks like the problem was my Firefox browser. If you Google "Fiverr cannot login with Firefox", you will see some of the problems that Firefox is infamous for.
And looks like it was a Firefox problem in the end.
I forgot to factor that in, and the fact that sometimes, the "cookie" or "security setting" in Firefox gets corrupted and Firefox will itself ban me from the site that I want to login....
I can login again, after clearing all cookies and deleting all saved passwords from JLForums.
Hope this info can help someone who faces the same issue. Firefox is very iffy in this regard, and also in a few other "mysterious" aspects.