On certain machines, after installing Visual Studio 2005, the contents of the Data Sources window disappears when a design surface that allows drag and drop from the Data Sources window is active. For example, the Windows Forms designer, User Control Designer, etc…

The cause of this issue is how VS processes the list of associated controls for each data type in the Data Sources window. When users customize the controls in the Data Sources window the settings are saved in the WinFormControls.xml file in the users application data folder. The version numbers in this file have been changed between beta releases and the RTM release and this mismatch of version numbers is the cause of the disabled Data Sources window. Basically this means if you customized the list in a pre-release version of Visual Studio and then install the released version on the same machine you might run into this problem as the installer for Visual Studio does not overwrite or remove this file during setup.

To fix this you have the following 2 options:

Option 1 fixes the problem but no customization is saved and the Data Sources window returns to its original state just like you installed a fresh product:

1)      Close Visual Studio

2)      Delete <DriveLetter>:\Documents and Settings\<UserName>\Application Data\Microsoft\Visual Studio\8.0\DataBindingSetting\WinFormControls.xml
Note:
For Express versions use:
<DriveLetter>:\Documents and Settings\<UserName>\Application Data\Microsoft\VBExpress\8.0\DataBindingSetting

Or, you can simply search for WinFormControls.xml under <DriveLetter>:\Documents and Settings\<UserName>\Application Data\Microsoft\

Option 2 fixes the problem and attempts to preserve any customizations you applied to the Data Sources window previously:

1)      Close Visual Studio

2)      Open the xml file (<DriveLetter>:\Documents and Settings\<UserName>\Application Data\Microsoft\Visual Studio\8.0\DataBindingSetting\WinFormControls.xml)

Note: see above for other SKU's

3)      Check if the version numbers of System.Windows.Forms are 2.0.0.0 (this is the RTM version)

4)      If the version number is not 2.0.0.0 replace the version number with 2.0.0.0

5)      If the version number is 2.0.0.0 delete the file (unfortunately prior settings will be lost, sorry…)

We apologize for any inconvenience this may be causing developers who have installed previous Betas or CTP versions of Visual Studio to help provide early feedback of the product.