Monitor Display problems

help please...

my monitor has been acting really strange lately...

first, the display gets cut in half then it will return to original size after about 5 minutes...

after that, the symptom displayed was that the display darkens and brightenss randomly...

finally last night, the monitor just went off, no display...but the ledpower indicator light is blinking, rather wildly...

i already tried removing and replacing the power cable...

any suggestion on what might be the problem would be greatly appreciated...thank you very much...