Hey there! Ive recently moved and I am looking to mount my flat screen TV on the wall of my new condo's living room... In my last property, I installed the TV on the wall in about half hour without a single glitch, but now, I am having problems.. Please note I am trying to mount th TV on an exterior wall (should be 5/8 drywall with 16" C/C studs here in Quebec). First of all, I am using the same stud finder as I have been using for the last few years (an electronic Stanley stud finder with digital display). This device has been working very well and Ive done several dozen of jobs with it, never had a problem. When the thing beeped, sure enough there was a stud behind. Now I am using the stud finder to "find the studs" but the problem is that the finder behaves very strangely.. In the past, my technique to double check and confirm, has always been to do a first pass on the wall, mark up where the finder would beep, and then perform a second pass coming from the opposite direction (lets say left to right the first pass and then right to left on the second pass). If the scanner beeped at the same location for both passes, I'd trust there was a stud behind. To summarize: -it beeps at irregular intervals.. (not every 16", but like 16 - 12 - 28... !?!?) -it doesn't always beep at the same place twice, it would beep about 3 to 4 inches away from the pencil mark I made during the first pass.. -sometimes, it doesn't even beeps on the second pass (like if the stud had disappeared..) Another technique I would use to double check, was to look for visible drywall screws and if they were aligned roughly with the location where the stud finder beeped, this would confirm there was a stud there.. What Ive also noticed with this job is that the drywall screws are all off by 3 to 4 inches from the location of the studs (as found by the finder). So what Ive done is to use a potential stud (because the finder beeped during both passes and there seems to be some drywall screws around there) and trace a line 16 inches apart (where the next stud "should" be). Then I've drilled a small (3/16") hole for my TV mount screws and discovered something funny.. The drill bit went through the drywall without problem. Then Ive withdrawn the bit and inserted a screwdriver to "poke" the stud and confirm there is something behind. Sure enough there is "something" but its 1 1/4" from the drywall face.. If it was a stud, it should be 5/8" deep (the thickness of the drywall sheet) right?? So I am clueless.. Could the stud finder be screwed up by electrical fields or something else? What have I "poked" behind the wall? Unless its something else other than a stud, this would mean that the drywall is not touching the stud which is not good at all.. All I know is that whatever I've poked is firm and sounds like wood (not mushy and spring like action like a wire or tube/pipe).. As you can see, its giving all kind of inconsistent results.. I cant trust anything. Should I simpy use the "possible" drywall screws or scan the studs some other way? Anybody can clarify/give guidance? Thanks!!