Hi Frank,
Thanx for your reply.
I've not yet tried testing the hex files successfully written by my programmer in any circuit.I'll try that now.

I loaded the hex file firmware (to be loaded in another 89c51 which is a part of my programmer circuit) using someone's programmer (which is the same as mine i.e. easy downloader v2) and it successfuly uploaded . But when i try the same with my programmer it gives a verify error.
Strange enough i can successfully write and read some HEX files using my microcontroller with no "verify error" at all.