We have had numerous problems recently with students being unable to open Mathematica files due to a "corrupt file cache." This page is simply a local (paraphrased) copy of information found at the Wolfram Research website (here) detailing how to recover from this situation. (It is up-to-date as of April 15, 2003; visit wolfram.com for updates.)

• Right-click on this link: Corruption.m and select "Save Target As...". Save it to an easy-to-locate place (e.g., "H:\Corruption.m").
• Open a blank notebook in Mathematica, and issue the command:
       Get["H:\Corruption.m"]
  (changing "H:\" to specify wherever you saved it.)
• Suppose that your corrupt notebook is called "Taylor Series.nb" and is saved in the "Calculus" folder on your network (H:) drive. You should issue the command:
       OpenCorruptedNotebook["H:\Calculus\Taylor Series.nb"]
  This command reads in the cells from the notebook and puts them into a new untitled window. Bad cells are unformatted, given a cell tag of "junk", and appear as red bold text. These junk cells can usually be safely ignored (and deleted).
• Save the salvaged notebook with a new name.