FIX: (Vista/XP/Server 2003): Desktop heap exhausted? Windows cannot open a new window, app, tab, menu etc.?

This fix enables Windows opening many more windows and start more processes. This is for people with lots of ram that usually open many windows (or IE tabs for example) and seldom restart their notebooks.

I use my 2GB ram a lot - I usually run multiple apps at once including Dreamweaver (likes memory and it has a memory leak btw), Fireworks, IE7 with 10+ tabs, Word (few windows), Access, WMP + usual stuff like Windows explorers, winrar, skype, gtalk etc... Now and then I also play games like fear and cs:s (steam).

All in all I usually use around 1,5GB ram and I don't restart often, but put notebook to hybrid sleep instead. And it is used like that for weeks. It is a very good practice since comp wakes up in seconds with my programs already started and ready, but it has one disadvantage - it sometimes uses all of Windows Desktop Heap resources meaning sometimes I cannot open a new tab, start new app or even get a rightclick menu! I need to close some window in order to free some of the resources. If you go to the Event Viewer/System you would find something like this: "A desktop heap allocation failed". It has nothing to do with free ram!

You can read an exellent article here: http://blogs.msdn.com/ntdebugging/archive/2007/01/04/desktop-heap-overview.aspx

Microsoft KB:

It happens on XP and Windows Server 2003 too. Vista is not an exception. 64 bit versions seem to have much more resources ready for allocation.

So how to fix it?

Fortunately heap size can be adjusted, but in registry. All registry edits bring a dose of warning and danger. Please be careful and read the following instructions:

1. Click on Start - and in search type regedit and press enter.
2. Go to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\SubSystems\
3. Make backup of your key! Click on File menu and choose Export. Give it a name and choose the destination. Click Save and there it is - a backup of your SubSystems reg key. Just in case you want the original key back.
4. Doubleclick on Windows key in the right pane.
5. In Value data field scroll left or right using arrow keys until you find this:
SharedSection=1024,3072,512. Change 3072 into 4096 so it reads: SharedSection=1024,4096,512

That is it! Now you can open more tabs, windows, start more processes and enjoy less restarts and shutdowns and more sleeps and hibernations. Good trick for notebooks!

I hope it helps. It helped me at least!

Cheers,

Ivan