An error occurred accessing a data source. An entry has been added to the Windows event log of the server.Log id 5566

ISSUE:

 

I tried to open the InfoPath form from the form library as web-browsable form and I fall on to this error:

An error occurred accessing a data source. An entry has been added to the Windows event log of the server.
Log ID: 5566
The cause of this error is the installation of .net 3.5 SP1. So to resolve this error you have to add key to the registry on all of the servers I have 2 WFE and 1 Application server. I had change the registry key on the entire server and restart the servers. The first server I restart is of course WFE on which my CA resides and the other WFE and then Application server. I think it’s always best to change first in Server on which CA resides.
SOLUTION:
I had followed these steps on all my servers and it works for me:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. Right-click Lsa, point to New, and then click DWORD Value.
4. Type DisableLoopbackCheck, and then press ENTER.
5. Right-click DisableLoopbackCheck, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Exit Registry Editor.
8. Restart the computer.

Reference: http://support.microsoft.com/kb/926642