Rectangular Marquee has rounded corners

I have PS CS on Windows XP. I'm not sure what happened, but my rectangular marquee cropping tool has developed rounded corners. It is sort of a hybrid of the rectangular and elliptical tools. I am unable to get back to 90-degree corners. I like the feature, but I didn't intentionally activate it. How to I get back to the 90-degree corners?
Thanks in advance for your help.

Could you have left a Feather amount (greater than zero) in the tool options?

That was it! Thanks Much!!! Don't recall changing it.