problem in open site in sharepoint designer The server could not complete your request

Hi

when i open my sharepoint site in sharepoint designer i got error and sit was  not opened,

it given error message boxes:

1)The server could not complete your request

2)An error occured while fetching data from sharepoint site un expected response from the server.

what was the problem.

so i tried to run the sharepoint product configuration wizard even i got error messge from it,

it given error message:

Internet information services not installed you must have .......

- even it installed

and  i already enabled IIS6 features

how to solve this problem.

adil