Perhaps Webroot is still blocking it? Other than that, I don't have any ideas off the top of my head - try posting the complete error message (CTRL+C should copy it); maybe that'll provide a better clue.
Also, which version and edition of Windows are you using? That might affect how you'd need to resolve certain issues.
Windows 7.
Upon launch it says: Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item.
I'm running it as administrator.
It should not be necessary to run as an administrator, FWIW, but it does seem to confirm that either something's screwed up with the permissions of the file (unlikely), or you have another program blocking PyLNP (far more likely).
Here's what you can do to check the permissions:
Method 1:
Right-click the file and choose Properties. Check the tab labeled Security. Make sure that the file has execute permissions for your user.
Method 2:
Open a command prompt. Navigate to the folder with the "cd" command. Type "icacls PyLNP.exe". Make sure your user has an F or RX permission listed.
I am not sure if Microsoft has enabled the Security tab in the Home editions of Windows 7; if not, you'll have to use the second method.
If you have the permissions, that means something else is blocking access to the file (I suspect Webroot). If you *don't* have permissions, something's taken them away (again, I'd suspect Webroot), but they can be reinstated. As a minimum, you should be able to open a command prompt as administrator, navigate to the folder, and type "icacls PyLNP.exe /grant Everyone:F"; if the Properties method worked, you should also be able to edit the permissions that way.