Invalid Image Buffer size ( 0 x 1 )

as per your screenshot you are trying to track an area smaller than one pixel, so the warning isn't a fluke. It also appears you are trying to work on an extremely small proxy twenty times smaller than the actual footage, which simply won't work. This is not an AE problem, it seems you don't understand the workflows and requirements for tracking. You have to track the original footage.

Mylenium

Also all of this was working till yesterday and works the first time after deleting preference file as if cache gets filled up and needs to reallocate memory

Thanks for your reply. 

I'm attaching the requested screenshots. 

A screenshot of the actual layer/ comp with the tracker would be more useful and of course we need info on the footage source. It could be some hardware acceleration, after all and just converting the footage might work, which is what I would recommend to try, anyway.

Mylenium