You might try downloading Process Explorer [technet.microsoft.com]. This can tell you what executables and DLLs a process is using and might provide some hint (look for the iexplore.exe process).

I just last night started having essentially the same problem with IE8, running on XP Pro SP3. It's not responding when I try to close tabs.

On the internet, it says that this problem can be caused by Add-ons but I have not had any new Add-ons recently.

I haven't either... though various security updates and patches, in my experience, do interact. The most recent is an Adobe Shockwave Flash Object dated 11/13/10 and I have that disabled.

There is a "Start Without Add-ons" mode for Internet Explorer that you can access by right clicking the IE desktop icon... not a shortcut, but the hard-wired icon on your Desktop... or you should be able to find the startup option via Start -> All Programs -> Accessories -> System Tools.

When I run without any add-ons, the browser works fine. When I've followed the step-by-step disable instructions and disabled the obvious suspects (but not everything), so far the browser still doesn't close tabs. Disabling my anti-virus software, another obvious suspect, doesn't change anything. I may need to disable everything else one by one, which will make for a long night.

I'm almost at my wits end. Came here to check out a post of mine from October [webmasterworld.com...] and see if that problem or suggested cures might be related.

After Thanksgiving, I may look into Process Explorer as Fotiman suggests. My difficulty is compounded by an intermittent problem my ISP has been having with its DSL service, which I thought might have caused a glitch in downloading an update file or some such.

FYI, two articles I've come upon re No Add-ons mode for IE...

Troubleshooting and Internet Explorer’s (No Add-ons) Mode
http://blogs.msdn.com/b/ie/archive/2006/07/25/678113.aspx [blogs.msdn.com]

Using the Internet Explorer 8 Add-on Manager
http://windows.microsoft.com/en-US/windows-vista/Using-the-Internet-Explorer-8-Add-on-Manager [windows.microsoft.com]

Note that the above articles may contain a combination of info for IE7, IE8, and Windows 7, but the basics have led me to the controls in IE8 on XP.

I had to fix this same problem today on an XP machine and IE8.
The fast fix is to go into Tools > Internet Options > Advanced and at the bottom of that tab is a Reset button.
It restores IE to original state and you have to do some tweaking to get it back to the way you want but it's quick.

I had to fix this same problem today on an XP machine and IE8....

...at the bottom of that tab is a Reset button.

Conard - Thanks. Is this a common problem, or is there some glitchy update that's going around?

Actually, just starting in "Start Without Add-ons" mode is a quick fix, but when I do that I've got to disable the add-ons one by one to find out which one is the problem.

As I understand the Knowledge Base article on resetting IE8, though, a lot of settings are removed or set to default when you use the Reset button, and that looks like it's more work than trying each add-on individually or in groups.

How to reset Internet Explorer settings
http://support.microsoft.com/kb/923737 [support.microsoft.com]

What was ultimately wrong on the machine you fixed? Was it an add-on, or is there in fact a way to screw things up with the other settings?

I'm not sure what the problem was but I suspect it had something to do with a Java update earlier in the week.
Before I reset the browser there would be several instances of IE running as viewed in the task manager when there were no IE windows opened.
The reset was pretty painless and took all of 10 minutes to reset the add ons and tabbed browsing to where they were before. Runs like NEW.

Well, it's bizarre. I turned some Add-ons off and on, and in different combinations, and it didn't seem to make any difference.

Eventually, after a reboot because the browser was crawling... as in s-l-o-w... there was an update for Adobe Flash Player waiting for me, so I did that update (to v10.1), and IE has been working fine since. Don't know whether the Flash Player was the problem or not. Anyone else experience this?

gouri... have you fixed your problem with IE7?

gouri... have you fixed your problem with IE7?

Robert,

Thank you for asking me about this.

I also apologize to everyone for not posting earlier.

For a couple of days I ran it with no add-ons because with the add-ons I could not close the browser. After a couple of days I used IE7 with add-ons and I was able to close the browser.

I guess one of the add-ons was causing the browser not to close and it must have been fixed. I am mentioning this because I didn't add any the day I started having a problem closing the browser or around that time.

Thanks to everyone for the helpful information.