Recently, I had described a problem that I'd been having with Win2K and XP. I know that someone else must have this problem because I was showing referrers from Google on various key phrases in the list of symptoms. In summary, here's the symptoms again

1. I can't Print from IE anymore (I get the following message: 'dialogArguments.__IE_PrintType' is null or not an object.)
2. <a target="_blank">, <form target="blank">, and window.open() don't work. window.open() fails with "access is denied"
3. I can't drag and drop files into any folder, my Desktop, an Explorer window or Internet Explorer.
4. I can't open up the Search page from the taskbar Start menu.
5. Certain MSI installers now fail while initializing.
6. I can no longer save web pages from IE (File | Save As) - the error is "the web page could not be saved to the selected location"
7. Outlook will no longer deliver new messages to my personal folders (on my local hard drive), and if I'm operating out of my personal folders, I can't send mail (the error is something like "the requested access is not allowed" when I hit the send/receive button.
8. The disk defragmenter doesn't work (both the analyze and defragment options).
9. When I try to debug a web application in Visual Studio.NET, I get an error "Attaching the Script Debugger to process '[3972] IEXPLORE.EXE' on machine 'WEAKLIEMG-XP2' failed. Error code 0x80070005"

It turns out that this is a known issue. KB article Q274696 discusses a fix for this. Basically, the root of the problem is this:

If the list of Access permissions is empty, the system and interactive accounts have implicit access rights. If a user or group is added to this list, the implicit rights no longer apply and only the users explicitly listed can have rights. This is a change in behavior from Microsoft Windows NT 4.0. In Windows NT 4.0, the system and interactive accounts maintained their access rights even though they were not explicitly listed.

So the solution is to open dcomcnfg, go to the properties page for Component Services | Computers | My Computer, go to the Default COM Security page, under "Access Permissions" click "Edit Default" and make sure that the local SYSTEM and INTERACTIVE users have "Access Permission" with the "Allow" checkbox checked.