Windows version?
=> Does this behavior persist if you start IE7 in No Add-ons mode? To start
IE7 in No Add-ons mode:
1. Right-click on the blue IE desktop icon and select Start without Add-ons;
2. Start > (All) Programs > Accessories > System Tools > Internet Explorer
(No add-ons).
More:
Troubleshooting and Internet Explorer’s (No Add-ons) Mode:
http://blogs.msdn.com/ie/archive/2006/07/25/678113.aspx
=> Does the problem persist if you Reset IE7 Settings (RIES)?
http://support.microsoft.com/kb/923737 <= Read before using!

Signature
~Robear Dyer (PA Bear)
MS MVP-Windows (IE, OE, Security, Shell/User)
AumHa VSOP & Admin; DTS-L.org
> I've been having some problems with IE7 automatically closing when I'm in
> the middle of reading a web page. It seems to happen more often when I
> have
> more than 1 tab open. Any suggestions?