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.
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Yes, likely receptacle is wired in reverse polarity. Turn off breaker, dislodge receptacle, check it out. The plug in testers are nice. You might want to test other outlets in your home. 
"Does it read higher voltage in the other outlets?"
Yes. I'll compare different outlets and stop using the bad one.
Thanks, Mesch. I'll test.
If you’re ok with pulling the outlet cover off and shining a flashlight in on both sides you may be able to see the hot (black) and neutral (white) wire going to the side screws, or if it is a back-stab connection you may be able to see which side black goes to and which the white goes to.  These wires need to be on the correct color screws on either side. ( Silver screw and brass screw. )

see attach link for details if you live in the US.  
https://i.pinimg.com/originals/a4/ba/86/a4ba86ca2eaa2d769727076a912e4452.jpg
If the colors are reversed from the image you have reverse polarity at the socket.  If correctly wired, as mentioned above you may have a loose screw connection or defective back-stab connection.  All are relatively simple corrections if you’re comfortable turning off breaker and redoing the wire connection.  Electrician is the certified answer but a quality handyman is quite capable of the same job at a lesser cost if you’re not up for the task.  
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.