Blot of discolloration, will degaussing fix it?

[P.H.U.]

I fired up the color test screens for MKIII (in MAME) and noticed that there is an area of the screen (a big blot) that is dis-colored. Is this a classic example of "Captain Degauss" to the rescue? Or do I have another problem?

[harveybirdman]

Green blob? Pics would help.

[P.H.U.]

I had a powerstrip hanging close by where the blot was showing on screen. Once I moved it, it went away. But I do see some darkening flickering on the bottom left corner. The PC is in that location. Perhaps interference from the PC is the reason for the discoloration.