Porteus

works fine here

More info needed. If you are starting from a vanilla Porteus with no extra modules added (in always fresh mode) I am sure you will find this is working fine. Most probably you have something extra added that has overwritten a file preventing you from logging in. If you can log in as root then open a console and type: passwd guest
Then follow the prompt and change the password to whatever you want.

Is there a peculiar reason why you hold so much to have unetbootin and porteus together on hdd?
Did you choose the specific partition on the hdd to install porteus? What is it? Is is for porteus only? What filesystem is it?
What is your bootloader?

I have LxQt/Porteus installed on both my USB stick and my netbook.
My USB stick and netbook also have a dual boot of Razor/Porteus.
here you go - many installations sharing saved changes which is causing conflicts. please refer to documentation and setup changes for each installation separately by using 'changes=folder_with_unique_name' cheatcode.

RazorQt means previous release and i have changed the way the changes are searched somewhere between 3.0 and 3.1. from now on booting media are checked first and then all devices in reverse order.