Problem:

If a user has created a .dat file from a Net Express application and then attempt to open\\update the file from a .NET Web Service, a 3/7 access denied error message returned from the service.

Resolution:

This is usually due to anm ASP.NET permissions issue, as the .dat file was created outside of .NET.

To set the correct permsiisons on the file in order to allow the Web Service to update it, the following must be done:

In explorer, bring up the properties for the data file, and select the security tab.  

Click Add and type YOURMACHINENAME\\ASPNET (where YOURMACHINENAME is the name of your PC) then click Check Names. This should resolve to YOURMACHINENAME\\ASPNET.

Now OK the dialogs and back at the Security tab, make sure ASPNET has full control over the file.

You'll also need to do the same on the associated .idx file.

Run the .NET Web Service and check that you can now update the file successfully.