Vista - XP SP3 and IE7 - can't click on various links after installing SP3

We have installed SP3 on our computers here and a strange thing has happened.
Mostly it's happening on laptops but I've seen it on a couple of our
desktops as well. When I go to a website that has a calendar to click on,
the calendar doesn't pop up (popup blocker isn't on!). Also, when trying to
log into websites, neither the ENTER key nor clicking OK will take you there.
Also, if I go to Start, Search, the assistant is there but the bubble that
is supposed to be above him that asks what I want to search for is missing.
Some users are also having problems installing applications from a CD, as the
NEXT button isn't working. And others can't print from Outlook. I have been
able to fix this problem on some computers by reinstalling IE7, but on other
computers my "fix" doesn't work. I've tried to research this online but
can't find anything. I know it's not happening to just us, as I have talked
to a few others with the same issue. Any ideas?