Vista - xbox360 not letting me stream files..unless i use Windows media ce

My xbox360 is wired into my computer running vista home premium...was able to
stream files perfectly for months..either using WMC or just the plain xbox360
media player (which i prefer over WMC)...but now my xbox360 is showing that
it is only connected to a "computer running windows media center"...and
showing that it is NOT connected to a "windows based PC"...thus only allowing
me to stream music using WMC. I havent changed any of my firewall or share
settings...etc.

the moment i first came across this problem when i connected my 360 to
computer..this message came up on my computer ("wmi reverse performance
adapter maintainence utilty" not working due to application..turning off). Im
not sure if this is related to the issue or not...

Any ideas? I need some help.