Right click the Start button, select Properties, Customize. Scroll through
the options on the Advanced tab and put the check mark back in Enable
dragging and dropping.
If your right clicking abilities are more complexed, run this edit.
To use the Regedit: Save the REG File to your hard disk. Double click it
and answer yes to the import prompt. REG files can be viewed in Notepad by
right clicking on the file and selecting Edit.