For some years I used Python with IDLE, including my Windows 7 machine.  In January IDLE stopped working.  Whenever I tried to open with file with IDLE, nothing happened.  No error message.  Nothing.

After some help from help@python.org I typed at the command line "C:\Python27\Lib\idlelib\idle.py -n" and I got this error:
IO Error: [Errno 13] Permission denied: 'C:\\Users\\Osk\\.idlerc\\recent-files.lst'

So I went to look at the directory .idlerc and found it empty.  No recent-files.lst. (Though it may be because it is a hidden file)

Now I think the problem is fixed - or at least for the time being.

I went to the admin identity and found that IDLE does open up there.  So I made a copy of the recent-files.lst file and emailed it to myself.  Then I went to my wife's identity.  And, again, IDLE opened OK.

Finally, I went back to my identity and renamed the file there to "recent-files-H.lst".  Then I retrieved the file I had emailed to myself and placed it into the .idlerc directory of my account as "recent-files.lst".

Suddenly I could open IDLE and run Python, as before!

The mystery remains - what happened?  When I compared the contents of the old recent-files.lst and the one I replace it with, the only difference I could find is that the old one had 17 entries, the new one had only one entry.