Receptacles and Lights Dim. Receptacle Tester Not Happy. Lights sometimes work?

Where would I be without family. Seems I may have lost a neutral somewhere in the circuit. Additional suggestions still welcome.

First of all, which country are you in?

In the US, white should be common so shouldn't be running to your switch and dimmer. It can be used if color marker is added to the wire to designate that it is hot. As drawn, it seems white is your line and red and black are the loads on switch and dimmer.

Your drawing makes little/no sense from a circuit standpoint without the connections at your electrical box shown.

A guess would be you are running the white/nuetral to the switch and dimmer and the hots are always at the ceiling and receptacle. That means that the dimmer and switch are acting as the neutral and causing you problems. The fact that you are getting a dimmed circuit at the receptacles says your switch and dimmer are wired wrong so you are completing a circuit through the dimmer when you shouldn't be. Testing with a receptacle tester will do you little good to troubleshoot your switch problems. You need to know what your circuit is before you connect anything.

I would strongly suggest you hire an electrician before you do anything else. The least you should do is spend the money for a DIY electrical book and the proper testing tools.