error enumerating data server. enumerator reports 'Unexpected error'

[smart.bug@gmail.com]

hi,
i have SQLserver properly running on my machine, when i open a
project in VB.Net and add a SQLConnection object, while setting its
connection string (when i click on combo box to choose data server) it
gives this error
" error enumerating data server. enumerator reports 'Unexpected error'
"
i need help on this very urjent please.
thanx
WaC