the given key was not present

In Visual Studio 10 I need to delete old Database connection but when do that it show
"the given key was not present" because i uninstall old oracle provider and add new one.
Now I can't connect to my Oracle DB

To fix this simply delete "DefaultView.SEView" in
c:\Users\[your username]\AppData\Roaming\Microsoft\VisualStudio\10.0\ServerExplorer

*Delete this file will delete all your connection so remember or backup your connection first.

How can make Visual Studio to support CSS 3.0 Validation

--- Obsolete please see bottom on update ---
This is CSS 3 Intellisense Schema
http://visualstudiogallery.msdn.microsoft.com/7211bcac-091b-4a32-be2d-e797be0db210

And if need more Html 5 support and CSS 3.0 full support install VS2010 SP1.

Update on 2012/11/10 (y/m/d)

After install VS2010 SP1 install this
http://visualstudiogallery.msdn.microsoft.com/a15c3ce9-f58f-42b7-8668-53f6cdc2cd83