Try this:
Use the run command:
Open "DCOMCNFG" to open up the Component services
Expand `component services' and `computers' and right hand click on `properties'
This would open the properties for My Computer and click on "Default Properties"
Ensure that
Default Authentication Level is
"Connect"
Default Impersonation Level is
"Identify"
if you cant find the run command hold down the windows key next to alt and press R this will bring it up.