Re: opamp
sivamit,
I believe that IanP is right. I believe what is happening is that the input bias current is causing the output to saturate, due to the mismatched resistances on the -(0 Ohms) and +(infinite Ohms) inputs. With the output saturated, the internal stages are probably also saturating, and drawing an abnormal amount of current, even though the output current is close to zero.
.
Even withh 1 Meg resistors, with a 5uA bias current (the spec limit for 5V supplies), the output could go as high as 5 volts. With an op-amp that has such a high bias current, you should use smaller value resistors.
Regards,
Kral