I was just wonder upon experiencing just that... 
 
I have a LCD-tv myself and haven't experienced this problem, but I had my Wii over at some friends house, and apparently the wii-remote can "lock on" to light from the plasma-TV instead of the sensor-bar, if you're directly in front of it. We did however solve this by hanging some mostly see-through fabric over the screen. Apparently that took what ever infrared light being emitted... or at least reduced it significantly for the wii-mote to only see the sensor-bar.
 
I thought nothing more of this and figured it was just a single freak occurrence with their pretty cheap Plasma-TV. However another friend of mine mentioned yesterday that his parents wii seem to have problem with aiming being inconsistent and jumping about. Since I know they have an 50" plasma, I told him about my first experience. 
 
The thing that makes me wonder, is that a quick search on google doesn't seem to report of other people having noticed similar problems with using a Wii on a plasma-TV. 
 
Just wondering if anybody has experienced something like this on their plasma set-up.

Never a Wii remote, but my friends Plasma TV did interfere with his Wifi connection.

No, I own a 50 inch Plasma from VIzio, and I've never had that kind of problem, and I play my wii all the time, as a matter of fact it actually works better on my Plasma than it does on my 47 inch Samsung LCD. Has yoru friend been abusing his sensor bar?

" No, I own a 50 inch Plasma from VIzio, and I've never had that kind of problem, and I play my wii all the time, as a matter of fact it actually works better on my Plasma than it does on my 47 inch Samsung LCD. Has yoru friend been abusing his sensor bar? "

Try changing the sensitivity in the settings. That doesn't change the speed of the cursor, it changes how much infared it picks up I think, so setting it low may make it so the TV's light is too low to "count" and only the sensor bar is tracked. This is the first time I hear of this issue too.
 
That settings screen should also show if it picks up more than just the two sensor bar lights, if more locations randomly blink or something.

" Try changing the sensitivity in the settings. That doesn't change the speed of the cursor, it changes how much infared it picks up I think, so setting it low may make it so the TV's light is too low to "count" and only the sensor bar is tracked. This is the first time I hear of this issue too.  That settings screen should also show if it picks up more than just the two sensor bar lights, if more locations randomly blink or something. "

Um, all the sensor bar is used for is the pointer's controls - via the infared camera embedded in the remote's front - and nothing more. The actual communication is unrelated bluetooth technology (unless the GH instruments use something else, but I doubt it). Therefor, even if you have infared interference from the TV, all that would be affected is the pointer functions, and "strumming" notes or other controls should all work.