With this trick you can play with u'r college pc...after this hack if some one opens my computer he/she'll not see any drive in my computer.Open Registry Editor by typing "regedit.exe" in Run or in command prompt. There you navigate to registry entry HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\Policies\Explorer Now in the right pane create a new DWORD item (by rightclicking and new->dword) and name it NoDrives ( case sensitive).
Now modify it's value by double clicking it and set it to 3FFFFFF (Hexadecimal) .
Restart your computer. So, now when you click on My Computer, no drives will be seen.
To enable display of drives in My Computer, simply delete that DWORD item NoDrives that you created (it can be deleted by navigating to HKEY_CURRENT_USER\Software\ Microsoft\Windows\CurrentVersion\Policies\Explorer and selecting the NoDrives and deleting it..del key...).
Again restart your computer.
You can now see all the drives again.