RPC error reinstallation?

Well I reinstalled XP SP2 then after working for awhile i noticed my sound
was not functioning. The icon was not showing up on the toolbar currently
running programs( which it usually does ). Then went into ADD\Romove programs
to uninstall.
I recieved an error " The RPC server is unavailable ". I then saw that sound
devices in Properties said it was not working properly, well after everything
I thought a SYSTEM REPAIR would work that didn't work eighter. Then i saw in
MSCONFIG there was one Service that was unchecked DCOM server process, this
service would stay that way evertime i restarted.
So I then reinstalled the sound software from a CD. In installation the
error code 110, RPC "server unavailable or has been currupted". could anyone
help?