Hi, everybody !
Just had the precise same problem just now, found the unresolved topic and found my own solution, thought I would share.
I must say as a foreword that I'm running wheezy, you windoz folks will have to adapt.
My problem arose from a change of home directory.
Here is the fix that worked for me:
Edit the file preferences.txt
Under Debian it was found in /home/yyy/.arduino/
Some links were left in absolute adressing and I had to manually change them to reflect the new state of affairs ...
Ciao a tutti