IE7 (?) sometimes closes no warning

Hi all, about a month or so ago IE just closed and rebooted by itself. I
happens quit offen on a -truck driving site-game that my husband uses. Also,
it would come up and say page can not be displayed. That happen today when I
was trying to log on. I would hit Sign In button put in user name and
password, Hit sign in, it would go to page can not be displayed. I went to
history clicked on a preveious page and it would show me Signed In. I don't
understand.
I am using Vista home prem. and IE7 I believe. On verizon network if that
makes a difference. It is also a desktop.

oh yeah, it doesn't just shut down on that driving site. it happens to me
also, just random i believe.