Do you have this issue with all the background images?
If no, the image file could be corrupted.
If yes, then I would advise you to repair the installation.
Start > Control Panel > Add/Remove Programs.
Select Orion Network Performance Monitor and click on Change.
Select the repair option and follow the steps.
Recall to re-apply the SP5 at the end of the repair.
Thanks for the reply.
I had installed several versions of Windows Server 2003/2008. In the end, I rebuilt the entire server.