When I try to upload a file to a document libary there is a long pause
followed by IE giving me this error: Internet Explorer cannot display the
webpage

The file doesn't get uploaded. On a may-be-related note, the Explorer View
shows the same error in the iframe.

Also, in the Event Viewer on the server this error is shown every time I try
to upload a file:
Event ID 1000, Source: Windows Sharepoint Services 2.0 Error Reporting
Faulting application w3wp.exe, version 6.0.3790.3959, stamp 45d6968e,
faulting module stswel.dll, version 11.0.8165.0, stamp 463656d3, debug? 0,
fault address 0x0005af9c.

I don't know what I did to start this behavior. Can anyone help me on this
one?