If you’re hosting Windows SharePoint Services v3.0 on Windows Server 2008/IIS 7.0 then you’ll eventually find that you can’t upload files around the ~30MB mark. The symptoms are as follows:
Single File Upload via Document Library
Nothing happens, you get a 404 page.
Multiple File Upload via Document Library
It seems to upload the file but then after the page refreshes, the file is nowhere to be found.
Single or Multiple File Upload/Copy/Paste using open with Windows Explorer
The file begins uploading but then towards the end you get the following error:
Could not find this item
This is no longer located in C:\filepath. Verify the item’s location and try again.
You can retry all day long but it won’t work. The solution is here: KB 944981