On a Win7 machine, have same issue in both Firefox and Chrome.
Periodically when trying to go back and edit a wiki page or adventure log page I get the following Error Message when I attempt to save my work :
2 errors prohibited this post from being saved
There were problems with the following fields:
* Name has already been taken
* Slug has already been taken
Here is the page I've most recently had this problem with.
Please advise and thanks for all the hard work!