Glitch in layout

Hey guys,
Im using dreamweaver MX now and for some reason, (and this happens quite
often) the layout when viewed in dreamweaver is completely off when previewed
in a browser. Im sure this is a really dumb question but I was hoping to get
some help. I now have to have it look "off" in dreamweaver in order for it to
look right in Explorer. Im referring to just tables and things like that. Any
help would be great. Thank you
Don