Hi
Yes, i already verify this problem.
I suppose that you guys are using the quickstart version.
Solution 1)
To fix this problem, please uninstall the JComments Component, JComments Content and user plugins.
Now, while removing the component, you might see some top notices and weird font size on administrator (don't worry about it).
Install again the JComment and now you should be able to save now.
Note: Uninstalling JComments will not erase comments on database.
Solution 2)
Without uninstalling the component, try to upload/replacing all files of this component.