A couple of times over the past few months, while in Visual Studio 2008 working on an SSIS package, I went to the toolbox and saw this message:

There we no tools at all showing up.  Apparently the toolbox became corrupted, but fortunately it is easy to fix.  Here were the steps I took to fix it:

1. In Windows Explorer, go to folder options and select the option to show hidden files
2. Close Visual Studio if it is open
3. Go to: C:\Users\YOUR_USER_NAME\AppData\Local\Microsoft\VisualStudio\9.0\
4. Delete the files toolboxIndex_reset.tbd, toolboxIndex.tbd, toolbox_reset.tbd, and toolbox.tbd
5. Restart Visual Studio and the files will be recreated. It will take a few seconds for the toolbox to repopulate