Modem works but can 't close SBC Express page

I went through the steps set forth by the installation CD but had to talk with tech support at AT&T to get the modem to work.
The SBC Express page, which appeared as part of the procedure is blank; when I try to close it, a message box appears, warning that the installation will fail if I try to exit.
I shut down the computer last night with that page still showing and it was back again when I started up today. It is still there.
The computer ran very slow at first but after about twenty minutes was back up to speed.
Still, though, I cannot close the page.
Any thoughts?