Hi, its the same situation for me. I upgraded to Desklickr 1.3.1 recently using DesckLickrs AutoUpdate functionality, and now it won't change my desktop any more.
I'm running Leopard...
While posting my problem in the post above, I searched my disk for Desklickr-directories, and found in my home directory:
.//Library/Application Support/DeskLickr
.//Library/Caches/DeskLickr
After closing DeskLickr and deleting both in a terminal using the commands
* cd ~
* rm -rf Library/Application Support/DeskLickr
* rm -rf Library/Caches/DeskLickr
and finally restarting DeskLickr again, it worked for me!