pic kit2 all protect error!

I am new to this forum.I'm having serious problem with my pic kit.I av been using it to program 16f877A for several times and everything is working perfectly.suddenly it just reading the pic and displaying all protect in red colour without modifying anything in the code or in the pic kit2 program.pls,can someone help me out.

Select a pic OTHER than the correct one and you will all 3FFF in the program memory area, then go back and select the correct PIC, use the drop down menu and deselect the Protection tabs. Now without doing anything else click the WRITE button. The PICKit2 will write 3FFF to the entire program area effectively erasing it. now load and program your chip.
Recently I bought a clone PICKit2 from SURE Electronics and it works fine except the lousy connector broke so I removed it and installed Std. .1 header pins. WHILE it was broken it mimicked your symptoms.

Thank u very archangel.the problem has been solved,I reload the pic kit2 firmware and everything started working fine again.I dnt know why pic kit2 firmware can be corrupted like that or may be there is bug in it.