SQL Server Create Database File Error I get the below error running a CREATE DATABASE script...

CREATE FILE encountered operating system error 5(failed to retrieve text for this
error. Reason: 15105) while attempting to open or create the physical file 
'H:\TestDatabase.mdf'


I am logged in as sa, which is a sysadmin.

What am I missing? 

CREATE DATABASE TestDatabase ON PRIMARY
( 
    NAME = N'TestDatabase',
    FILENAME = N'H:\TestDatabase.mdf' , 
    SIZE = 51200000KB , 
    FILEGROWTH = 1024KB
)
Don't put your database files on the root of any drive. All kinds of things go wrong here, especially if you have UAC enabled.

Create a subfolder, like H:\Data or H:\Log, and put the files there, making sure the SQL Server service account has read/write permissions. Or use the actual instance data/log folders, which should already be set up permissions-wise. You can change those, too, if they're currently in a not-so-optimal place (like somewhere on C: &lt;shudder>).

(Also, your CREATE DATABASE command is missing a LOG ON specification, dictating where you should put your log file.)