Drag 'n Drop / Copy Paste not working among other GUI problems - SOLVED

I had this problem on a server an someone asked me try to resolve it before doing a fresh installation.

Windows 2000 / Windows 2003
Sympthoms :

When you Control-C (copy) files,text,images,anything / Control-V (paste), nothing ocurrs

When you click Web page hyperlinks that are supposed to open in a new window, nothing occurs.

When you right-click a hyperlink on a Web page and then click Open in New Window, nothing occurs.

When you click a hyperlink in Microsoft Outlook or in Microsoft Outlook Express, the hyperlink does not work.

When you try to drag an item to the Start menu or to any folder on the system, the pointer changes to a circle that has a slash through it, and you cannot drop anything.

When you click Find (on This Page) on the Edit menu in Microsoft Internet Explorer, the operation may not work or may work only one time.

When you click Start, click Search, type all or part of a file name in the All or part of file name text box, and then click Search, nothing occurs.

When you click Start, click Search, click Other Search Options, and then click Search the Internet, nothing occurs.

When you try to start Microsoft Office Assistant, you receive the following error message:
Problem occurred using Office Assistant, Do you want to reinstall it?

When you try to drag a file from Microsoft Outlook 2000 or from Microsoft Office Outlook 2003 to a folder, you receive the following error message:
Cannot create another system semaphore.

You cannot print from Internet Explorer.

You cannot print HTML messages in Outlook.

When you click Start and then click Windows Update, nothing occurs.

When you try to download an update from the Windows Update Web site in Internet Explorer, Windows Update appears not to function. Although you see the "Preparing to Download" message, the progress indicator does not change

Yet, if you trying doing these things through a command line without using the GUI it works. So what's the problem : someone messed with the components.

Solution :

To work around this issue, locate and then delete the DefaultAccessPermission registry entry. To do this, follow these steps:
Click Start, click Run, type regedit, and then click OK.
Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole
In the right pane, right-click DefaultAccessPermission, and then click Delete.
In the Confirm Value Delete dialog box, click Yes.
Exit Registry Editor.
Log off the computer, and then log back on to the computer.

It took me a while to find the kb/900960/ because they didn't include the copy/paste sympthom.

Just after those magic steps, the server began to work properly and I didn't have to make the reinstallation (having found the solution on the day previous to the reinstallation, lucky me).