Using PM 4.6.5 on Intel OSX 10.6.4
When selecting "File->Save Photos As..", it seems there needs to be error checking for a blank "Rename as.." field.
The problem is that I waited about five minutes for the save operation to finish, only to discover there were no files generated due to my error...so I had to redo the process again, this time dechecking the "Rename As" checkbox.
Reproduce steps:
-Select photo(s) in the contact sheet
-Go to File->Save Photos As
-Check the "Rename as.." box, but leave the textbox and sequence number checkbox blank
-select the "Always pick destination" radio button
-Create a new folder and Save the file(s)
-The new folder will remain empty, (sometimes a "could not complete save operation" error message will appear, sometimes not)