USB ports having sudden difficulties please help!

hey all,

this is about my old machine running avg 2 years old. specs are as follows:

p4 3ghz w/ ht 90nm

asus p4s800mx-se sb sis 964
nb sis 661fx

1gb of ddr 400 ram


problem:

one day ( 3 days ago) the usb ports ( all of them) stopped working on external hard disks. i tried my 512mb mp3 player and it worked allright but if i put in a 512mb flash disk it wont acept it. windows will say the usual like your hardware is now ready to use then another popup says, usb device not recongised. one of the usb devices attached does not work properly. the really bugs me out because my usb mouse seems to work w/o a hitch. the external also works on my other computer ( see sig) and i got so pissed i reinstalled windows. currently im using a fresh copy of xp sp2 but still no results. so being a software problem is out. could it be the mb thats causing this? but if so why is my mouse still working! also, the printer doesnt work anymore. its a cannon ip4200 which also happend to stop working when the e-hdd stopped. wahts happening guys?

yeah ive thought about adding a card too, im getting my dad to get one
but btw, the native ports dnt work ether

im trying to hold off on the card in case theres somthing else

the external hdds are externally powered. and the mice isnt but it works. usb flash drives dnt ether

heyy all =D thanks for your replies but for now.. ive got my dad to buy a pci usb 2 card. it works with everything now so i guess my problem was solved... ill take your words that the mobo is failing. you guys should see anotherrr new build thread soon i mean.. who still supports skt 478?

THANKS FOR ALL THE SUGGESTIONS =] ( ive copied and pasted this thread for reference ^^ )