Windows seems to have a limit of how many windows it can have open at once-- and IE seems to be the worst culprit. When the limit is exceeded (e.g. 60 IE windows open at once), I get really odd behavior like a gray blinking screen with random chunks of the IE user interface showing up in random spots on the screen. Once I close a few IE windows (with Alt+F4 since I wouldn't know where to click with the mouse) the problem goes away.

This is Windows Server 2008 and IE8, if it matters, but I've seen the same behavior on all Windows OS's since XP and all recent versions of IE. I have 4GB RAM and a big swapfile, and task manager doesn't even show me using 3GB, so I'm running out of memory overall-- instead there's a special kind of windows resource that I'm exhausting.

I remember reading years ago (in an aticle I can no longer find) that there was a registry setting that you could increase the limit of windows (or just IE?) to allow more windows to be open before Windows barfs.

Yes, I realize an easy fix is to close all 60 IE windows, but often I'm in the middle of researching something and don't want to deal with the hassle of re-opening 10 of those windows that I really need.


Two articles seem to offer solutions to your problem:

1: Increasing the maximum windows? says:

Open Regedit & go to: hkey_local_machine > system > currentconrolset > control > sessionmanager > subsystems
Open up the Windows string --- there is text in there that includes SharedSection=1024,3072,512 If you change that to SharedSection=1024,4096,512 then you will be able to open up more windows.

In my vista the value is actually 1024,12288,512, so I'm a bit skeptical about this advice.

A second and perhaps better article is:

2: Desktop Heap Overview which says :

Every desktop object has a single desktop heap associated with it. The desktop heap stores certain user interface objects, such as windows, menus, and hooks. When an application requires a user interface object, functions within user32.dll are called to allocate those objects.
Session view space for a given session can become fully utilized, so it is impossible for a new desktop heap to be created.

The article goes on and describes how to diagnose the problem using a free tool, and how to increase this space by adjusting the registry entry of
KEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management

  • this rocks. is exactly what I was looking for. thanks for the detective work! – Justin Grant Oct 16 '09 at 1:37

Is there a reason you can't use Firefox instead? To be honest, I have had better luck having lots of windows open that way than with any version of IE. Also, does using multiple tabs make it work any better, i.e. you can have 10 windows open with more than 6 tabs each equaling over 60?

  • Yep, I'm doing a lot of IE-specific testing. Hence the IE overload. But IE is just one of many apps I tend to have lots of windows open at once... would love to solve this for all apps. I've never been a fan of tabbed browsing because I like to use Alt+Tab to flip back and forth between apps... tabs in IE or FF messes this up. – Justin Grant Oct 16 '09 at 1:36
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    I know tabbed browsing took some getting used to for me, but you can use Ctrl+Tab to switch tabs, and the Alt+Tab when you want to switch to another app. It works for me but to each their own. – Joshua Nurczyk Oct 16 '09 at 13:41

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