Skype saves chat history despite setting to save no history

I have noticed that even though I have the setting under the Privacy tab to save "no history" that it still keeps the history of the last conversation.

It happens even across different portable instances. For example, I use Skype Portable at a friend's house from my thumbdrive (settings set to no history), have an IM conversation, exit the app.

Then I go home, maybe the next day, launch Skype Portable from my hard drive (so totally different set of files), when I log in I see the conversation history.

Does anyone else experience this or know a fix?

Thanks.