i would suggest you open a support case and let support walk you through using 'Repair' on your NPM installation. in most cases that seems to fix these type things. good luck...
I would look in the event log for clues... possibly open a case if you are under support. Another option would be to re-install with the repair option.
Dang lchance you beat me too it :}
I guess we were basically thinking the same thing <g>
Definitely follow the advice of the esteemed posters on this thread. Here's a quick way to Open a support ticket here.
Click Submit a Technical Support Ticket
In order to receive technical support, you will need to be current on your SolarWinds maintenance. Complete the form. You will not be able to upload your Orion diagnostics, but you will receive an email back that allows you to upload diagnostics.