Windows 7 locks shortcuts to the taskbar

I am a true system enthusiasts, Windows7 Beta just came out when I downloaded the first time to install in their own, May 5, Microsoft announced the release of the WINDOWS7RC version, but also the first time to put a new version. Windows7 humanized operation and Beautiful window has always been my favorite, which windows7 a more distinctive feature is the window cascade, you can allow users to lock some of the program shortcuts in the taskbar, which provides a lot of convenience for user operation, especially in the open window more than a few, This feature is especially handy, and you don't have to show your desktop to open a program.

When surfing the internet in the last few days, when the mouse right click on the taskbar IE icon to select the site, because the operation is too fast and delayed the "unlock this program from the taskbar" option (Figure I)

Then IE disappeared from the taskbar, I tried to restore it, but open ie, right-click the taskbar ie icon, without the "lock this program to the taskbar" option (Figure II)!

and open IE directory to drag ie to the taskbar, there is a red fork is not available tips. I tried to drag another program to the taskbar, and there was the same hint.

Search on the internet for a long time, according to the online method also does not work! In anger, I decided to take care of it myself. And then calm down to think about what they have done to the system before, such as optimization and so on ..., suddenly, I think of the system is that I have deleted two registry key values (Hkey_classes_root\ Isshortcut in Lnkfile and HKEY_CLASSES_ROOT\piffile) to remove the small arrows from the desktop shortcuts.

Is it the effect of this? I will restore the 2 keys again, and all the problems will be solved.