I have 300 gig of open space on drive C yet, I got a drive full warning. I used an old program call Space Monger to find out Topaz was saving hundreds of large temp files on drive C. I looked to see if there was a preference to move to another drive, but no such setting.
Steps to reproduce issue:
Process 1000 files in five groups
Drive C full warning
3.delete all temps and problem solved
Also if you can, please try to recreate this error message in Topaz Photo AI, then go to Help > Open Log Folder, please send me all of the files within that folder. You should be able to attach them directly as a response to this email.
You can securely submit your files(s) to my Dropbox using the link below. Please be sure to send me a note to let me know you sent something.