I once had a user phone me up complaining that her Word was not working properly and kept on displaying rubbish on her screen.
As this was back before we had any sort of remote access to users pc's so a desk visit was in order and a short walk to think over the possibilities.
I arrived, borrowed the mouse, found a Word document on the network drive and opened it with no problems.
Then I asked the user to show me exactly what she was doing: she went to the file menu, chose open and selected the Word document she wanted to edit which then opened displaying all of the internal document formatting and the plain text of the document..... all in Acrobat Reader! :D
I then spent about 30 minutes training her in how to use Explorer/My Computer icon to find and open files in the correct program and what the file type filter was for in the Open dialogue box. Quite how she had worked for about 5 years in the office using computers without a similar issue cropping up was beyond me.
When I left the place last year, she had still barely improved her computer skills and still insisted on following along "monkey see, monkey do" style without giving a thought as to what and why she was doing something :)
Another anecdote from the same user was that she created a letter template in Excel and had terrible trouble with the layout changing each time she updated the text in the letter, the crazy thing was that she used Excel rather than Word because she had no idea how to use tables in Word and didn't want to ask anyone in her department for fear of being seen as IT illiterate... as she said she was IT trained during her interview. Quite how she managed to retain her job I have no idea; she must have had something over the company or just managed to retain a very low profile.
It still makes me chuckle even now 10 years on from that initial incident and the company still hires people of similar IT skill calibre today :)