Thanks for the quick reply. Can't seem to find any errors specific to .Net Framework or PopGrabber in Event Viewer under either System or Application or PopGrabberLog. I've attached an image of what I see in the settings:

It's not perhaps a missing control or anything like that at all? I've also enabled the debug logging level in PopGrabber but as you can see in the above screenshot, it doesn't appear to register as a problem.
Oh yes, I haven't installed SP 1 for .Net 1.1 as .Net 2 is installed. Unless I must uninstall 2 and install the .Net 1.1 redistributable? And I did come across the following but for HHCTRL which I think are for changes made to fix what was broken by Microsoft Security Update 896358:
Event Type: Information
Event Source: HHCTRL
Event Category: None
Event ID: 1904
Date: 10/05/2006
Time: 16:09:00 PM
User: N/A
Computer: ORTHANC
Description:
The description for Event ID ( 1904 ) in Source ( HHCTRL ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event:
http://msdn.microsoft.com/netframework/downloads/framework1_1/,
http://go.microsoft.com/fwlink?LinkID=45840.
Only included it as it makes a reference to the .Net framework.