boost converter circuit behaving strangely
simulate this circuit &ndash; Schematic created using CircuitLab

Most probable cause is that inductor goes in saturation. If we ommit the resistance of the inductor, then the current trough inductor is $$ i_l=\dfrac{1}{L}\int u\cdot dt$$ where u is the voltage, for example 1.2V and time is 0.8*1/960 = 0.00083, so the peak current is: 1.2*0.83/100= 10mA.

Check the inductor data what's the saturation current. 

EDIT: 

It has to be noted, that this exaple is oversimplified. The main simplification is that current is trough inductor is discontinouos. For better explanation you should use some simulation software.

You can click on simulation.