OE5 tab function changed

I first noticed when I start an e-mail after entering the name of the recipient I use the tab key to go down to the subject and then when filled in I use the tab key to get to the body of the letter. Now when I press the tab key if I am in OE it takes me to the in-box list page. I can't think of anywhere to change the function of my tab key unless it is starting to act up and this is it's action from being worn out.
Also I noticed when not in OE the tab function has changed. If I have any windows minimized they maximize when I use it as a toggle key would be used.
Any ideas how to revert to the "next line function" I was enjoying before?

 

The Tab key seems to have reverted back to it's original function. Could have been from a reboot although I think I had done that. Anyway I seemed to have had the problem fixed now. Thanks for the chance to ask.

 

I see that all the time and it drives people crazy! It's usually just a stuck Alt key or something. If it happens again, tap them a few times - should go away.