[AT] Chain saw cutting issues

[David Trompower]

I have a [U]Poulan  18 inch classic, chain saw.   [/U]    and had it for years.
Today though, I have issues with the chain blade.

the chain is but 2 months old.  it now will only cut the soft outer wood of a log and stops when it reaches the hard wood of the center of a log. It is nut cutting straight through a log.  Instead, it is cutting in such a way, that by the time the blade reaches the hard wood...  my left hand is in the air and my right ( which is operating the throttle)  is down, and the blade has cut a curve? a curve that  heads in the direction of my left leg.
SO I sharpened the blade teeth and filed down the  blade depth gauge just a bit...( using a Oregon,sharpening device to do so). 

[U]I am [/U]getting short chips  off the blade but the saw shows no improvement in cutting abilities and continues to  cut a curve . ???

I have resharpened  and resharpened and even sharpened only the left cutters,  No improvement. 
 then only the right cutters, and no improvement? 
maybe I need to sharpen yet some more the teeth on one side more than the other?,.... but which...the left cutters or the right?

And it seems that once the blade reaches the hard center wood of a log,  the only way I can get and  more shavings is to rock the saw  ( tilt it  left and right in a rhythm,)  but it cuts a deeper groove towards my left leg.  

Tell me what is causing this curved cut issue ? and how do I correct it?
and why the cutting stops when I reach the hard wood in the center of a log?

R. David