Strange Issue that I am not positive is 100% TV related

So I have a Samsung PN58B650 that I had the panel replaced under warranty to try and fix the buzzing. So after we got it back together and hooked back up it seemed to work fine, but later that night it developed this thick magenta line from top to bottom (probably an inch wide or so). So the tech said that it needs another new panel, so they actually picked up the TV today to do it at their warehouse rather than in my home.

Anyway, the dropped off a loaner (which sucks BTW and is only 37 inches and not 1080p) so I just hooked it up and went to work. But when I got home tonight I noticed that this loaner TV has a thin magenta line from top to bottom (roughly 1/3 the way across the screen from the left which was roughly the same spot as my actual TV). This line is significantly thinner (only a couple of pixels wide), but it seems VERY strange that this is occurring. I don't know what could cause it other than a bad panel, especially since nothing has changed in my setup since trying to replace the panel on my TV.

Is there something that can be "frying" panels causing these magenta lines? That doesn't really seem possible, but it is seems VERY strange that it happened on two TVs in roughly the same spot (proportionally). I am afraid to try another TV.

Nope the line on my TV and this loaner is there every time I power on the TV, even if all inputs are unhooked. Plus, I didn't add any new equipment to the house since the first attempt to fix my TV so it would be really weird for that to all of a sudden be a problem. Not to mention that I have a 32" TV in the bedroom probably 15-20 feet away that works fine and a 42" TV about 15 feet or less the other direction that works fine.

I decided to take a chance with my new 42" 3D TV that I just bought and hooked it up and everything is fine so far. I am within the return policy for the 42" so if something goes wrong I can return it. So I am going to leave this one hooked up for a while and see if anything happens to it. If not, then it may have just been a really weird coincidence that the loaner also had a magenta vertical line. I wish I looked at it when I first turned the loaner on to see if it was there initially. Either way, I am going to call the company tomorrow and make sure I let them know so they don't try and charge me or anything.

Yes, I plugged the new TV in to the same HDMI cable and same outlet in my Belkin PF-60. So everything was the same. My old TV worked fine in terms of now vertical line, but I tried to get it fixed for he buzzing so they replaced the panel. The "new" panel wasn't 100% working because we actually had to swap the digital board from my TV to the new panel because the one in the new panel had blue and red dots everywhere. Once powered on, the TV appeared to work fine, but later that day the vertical line appeared and never went away. Once in a while it would "fade" a little like it was trying to go away, but never did.

I didn't check the loaner TV when I first powered it on, but when I got home from work, I noticed that it had a line down it as well and it doesn't go away either, but it is not as bad as my TV was.