ive recently run into an issue with my yamaha EG112, on my lower strings (b & e, the top strings if you wanna get technical) when i strum them together i get this annoying noise as if something is loose and rattling, however when i strum them seperately this does not happen, i hear in most cases its the truss rod but i wanted to see if anyone else had any other ideas before i went messing with that, im not comfortable messing with it as i have no knowlage of it; so if it is the problem id would like if someone could tell me what i needed to do.

thanks in advance.
forgot the mention that the noise comes from the upper neck area near the nut.
try tightening the bolt on the place where you loop your strings. most likely it's loose.
Don't just jump to the truss rod... unless it's so loose it's rattling.. Check out the bridge saddles make sure everything's tight. check the string height... try raising that.. check tuners... does this guitar have a locking nut setup? Lots of things to look at before the Truss Rod..

of course if you look down the neck, and it's a ski slope... Well.. the truss might need some adjustment...

Hard to diagnose without actually seeing the instrument... Hope this helps...
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thanks guys, ill try the string hight thing and i also forgot to check the bolts but i think last i checked they were solid.