Constantly getting "Loading toolbox content from package" in Visual Studio AND IT TAKES FOREVER!

This usually happens when opening the Toolbox (CTRL-ALT-X), or moving the mouse over the Toolbox icon (which appears on the left).

According to this Connect issue report, there's a workaround to be done, which may fix the issue:

He said he simply removed the registry key under:

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\   VisualStudio\10.0\Packages\{D766DAA8-F81E-4621-9184-F21C7F389796} 

and the problem went away. Read more on that link.

• Be sure to take a backup of whatever registry changes you make!

I was facing the same problem and also tried to solve it by deleting to registry key(s). But the problem returned after a while.The keys where back again.

But, I found at each key has settings for toolbox with the value 1, like:

...{2c298b35-07da-45f1-96a3-be55d91c8d7a}\Toolbox]"Default Items"=dword:00000001

You can find this setting in the C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\ShellExtensions\Platform\BaseConfig.pkgdef, line 8395.

I changed the value from 1 to 0 ("Default Items"=dword:00000000) in all {2c298b35-07da-45f1-96a3-be55d91c8d7a}-keys and the file mentioned before.

The problem seems to be fixed, since over two weeks. The fix before worked less than one day.

1. Start Visual Studio 2010 commandprompt
2. type in devenv.exe /log "c:\Users\\Desktop\vslog.txt"
3. Just work normally in your visual studio 2010.
4. after your work close visual studio and check the log file (vslog.txt)
5. Search for "package load took" or "2C298B35-07DA-45F1-96A3-BE55D91C8D7A"

You might then find something like this:

  <entry>    <record>574</record>    <time>2012/09/14 07:36:45.386</time>    <type>Information</type>    <source>VisualStudio</source>    <description>Toolbox: package load took 0 ms, ResetDefaults call took 12230 ms</description>    <guid>{2C298B35-07DA-45F1-96A3-BE55D91C8D7A}</guid>  </entry>

Now you can search the registry key and delete it (make sure VS2010 is closed).

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\VisualStudio\10.0\Packages{2‌​c298b35-07da-45f1-96a3-be55d91c8d7a}] 

Maybe you will see other clues to your problem in the log file.

Make sure you BACKUP the registry or any other settings you make.

Learn more about visual studio switches:http://msdn.microsoft.com/en-us/library/xee0c8y7(VS.100).aspxThe bug report on Microsoft Connect: http://connect.microsoft.com/VisualStudio/feedback/details/735555/silverlight-5-tools-bug-loading-toolbox-content-from-package-microsoft-visualstudio-ied-toolboxcontrolsinstaller-toolboxinstallerpackage-2c298b35-07da-45f1-96a3-be55d91c8d7a

extra info: http://michaelcrump.net/fixing-a-broken-toolbox-in-visual-studio-2010-sp1