webpages don't fully load.

This is an intermittant problem. It occurs consistantly
with ebay, but I can't think of where else it has
occurred. From page one most of the links show up and
work, but there are large areas of white/blank space. If
I click on "sporting goods" the next page comes up, but
with blank space. Then, when I click on "cycling" for
instance, the ebay banner comes up, but the rest of the
page is blank. The taskbar says "Done" and there is no
vertical scroll bar (its faded/inoperable.) Please help.