Scott,
Emergency measures...
From IE> Tools> Internet Options
or
Control Panel> Internet Options> Advanced> uncheck "Enable third party
browser extensions."
Or, run msconfig. Look at the Startup tab for suspicious entries. Uncheck
any suspicious entries, restart, see if IE opens.
Go to C:\WINDOWS\Downloaded Program Files (or C:\WINNT...) Check properties
of each object, delete any suspicious objects.
If IE then functions, go to http://mvps.org/winhelp2002/unwanted.htm and
start working through the solutions. There's a good chance that a
parasite-type program is causing this.