Sql 2008R2 instllation on Windeows 2008R2 - Service Account Error in log after installing

Hi,

I have installed sqlserver 2008R2 on new m/c as a part of migrating from sql
2005 to sql 2008.
Next day I was looking the log and found the error
message:

Login failed for user 'MSSqlDB2K8\sqlsrvAcct'. Reason: Failed to
open the explicitly specified database. [CLIENT: <local machine>]

I have created this account during installation but didn't add account int
oadministrator group.
I have also tried to login using same credential in
SSMS and I can't connect.
When tried to sto pand start the service i can do
it.

I have added user into Administer group but still not working.
I
have also assigned account in Sysadmin server Role into Security.

Thank
you!