Fellow seniors wondering if any of you have had this problem?

[Dave M]

I get a red line under my E-mail address every time I log into my yahoo. web site, same kind of line you get when you miss spell a word. Now I have no problem sending and receiving messages or logging into yahoo answers but when I try to get information, communicate with companies or set up twitter account I'm informed I have an improper E-mail address.
With my limited computer ability I've tried my best to correct the problem - seem like all I'm doing is butting into walls......would be grateful for any suggestions.