Line fault at the outlet -- do I need an electrician?


Yesterday, I got a Panamax, Max 1500 surge protector and line conditioner. (I got a very good deal on it, and am just trying it out.)

I plugged it into an outlet I've been using for a while and one of the red lights on the front lit up saying "line fault." (I'm not sure how this is different from a "ground fault." Maybe it's the same.) The Panamax does not do this with other outlets in the room. They seem ok.

So, I know this means that the outlet is improperly wired. My question is, might this be a simple thing to check and/or fix? Any suggestions most appreciated. It's the only outlet I can use to have my audio set up where I usually have it. Now is not an optimal time to call an electrician. If this is a big problem, I'll try out my gear somewhere else in the room, but if I can fix this without too much expertise, that would be ideal.
128x128hilde45
Thanks, Bryhifi. I think I could at least take a look. It's two different outlets that have the fault -- one feeds the next one. I wonder if correcting the root might also correct the branch.
hilde45,  that is a possibility if the feed going to the line side of the first outlet is reversed and the daisy chained outlet is wired in parallel off the load side of the first outlet in correct polarity. 

https://solitum.net/content/images/2015/08/62304C67F7C8465FB3B153929E16E752.jpg
Yes, it's usually the first one that needs fixing which fixes the next in line.
I would get that plugin tester for the rest if the house anyway and make your job easier.
Good luck
@bryhifi I have a digital multimeter. I use it to test car batteries. I suppose I might use that, too, no? In any case, I can get the three prong outlet if necessary. Thanks for the picture you sent -- I've saved that.

@cissado @heaudio thank you for your advice, too.