I have uninstalled sql server 2008 and try to install sql server 2008 r2. Analysis service uses the local window account (User id is ivykwok and password is ivykwok)
But the following error is shown.
The credentials you provided for analysis services service are invalid. To continue, provide a valid account and password for analysis services service.
When you install SQL Server 2008R2, did you login as ivykwok? if so, I think you can try "Add Current User" button to add that user, so that you can use that user on Analysis Service.
If I mis-understood your issue, maybe you can try to move this post to SQL Server and Business Intelligent section in this forum. I think you can get more help about SQL Server easiler
Please find the SQL Server and Business Intelligent section URL below