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Originally Posted by Neoxter

A very useful trick to lock a FOLDER. This trick has only been tested in Windows XP.

Suppose you want to lock the folder "test" in d: which has the path D:\test. In the same drive create a text file and type
ren test test.{21EC2020-3AEA-1069-A2DD-08002B30309D}
Now save this text file as lock.bat

create another text file and type in it
ren test.{21EC2020-3AEA-1069-A2DD-08002B30309D} test
Now save this text file as key.bat

Now you can see 2 batch files lock and key.Press lock and the folder test will change to control panel and you cannot view its contents.Press key and you will get back your original folder.

Well, let's explain things more here...
lock.bat is renaming the folder "test" and giving it a CLSID extension, so the folder now is referring to another object...
key.bat is restoring the folder "test" to the its original state by removing the CLSID extension, so the folder will be accessible again...

What is a CLSID?
A Class ID (CLSID) is a 128 bit (large) number that represents a unique id for a software application or application component. Typically they are displayed like this "{AE7AB96B-FF5E-4dce-801E-14DF2C4CD681}".

You can think of a CLSID as a "social security number" for a piece of software, or a software component.

What are they used for?
CLSIDs are used by Windows to identify software components without having to know their "name". They can also be used by software applications to identify a computer, file or other item.

Where do they come from?
Microsoft provides a utility (program) called GUIDGEN.EXE that generates these numbers. They are generated by using the current time, network adapter address (if present) and other items in your computer so that no two numbers will ever be the same.

So we can use the CLSID of another object, not just control panel...
:)