access denied-file in xp-continue????

i can not access video file in my shared folder.(few of them).
said access denied can not play 0x8070005
now after your answers i have found that
this files have ca root certificate which is not trusted because is not in trusted root certification autority store
version is v3
public key xxx
valid from2004 until 2104 :((((
so big question is::
what next???
if you ask me how did i create this would never have a clue.
can i remove it and how ?
or where is that trusted root store???
tnks

Have you tried downloading the latest root certificates update from the Windows Update Page?

NO
BUT MAYBE WITH AUTOMATIC DOWNLOADS ON THATS POSSIBLE
OR MAYBE INSTalling sp2 have something to do with it
(sry for a capit letters realized late :)

I'm not sure if AutoUpdate covers Optional Updates as well as critical, I update manually. Internet Explorer>Tools>Windows Update will take you where you need to go to check.