Blank screen on dual set up

im having big problems, i have a ati radeon hd4670 512gddr3 card and a hp w2216 and teac lcd tv (that is able to link up to a pc via vga)... when i first set up the 2 to my graphics card they seemed fine, worked for awhile, but after restarting my pc the second screen seemed to just appear blank? it was on during the whole boot up process but as soon as it enters user screen it still goes blank?.. i thought it maybe a windows problem so installed xp again, but still a blank screen... iv swapped around the sockets connections on the card and both screens seem to work on both displays? just cant seem to run 2 at the same time... even though i can drag things into the other screen while it is blank? iv played about with all the settings and still havent come up with anything... they are both install correctly and both enabled in the setup.. i really have no clue what is going on... maybe some sort of switch over thing gone wrong.. but beyond me... can anyone please help