Apple has had this annoying Finder bug since version 10.5.3 which causes issues with WebDAV file copies. This issue is still not fixed in the latest Mac OS X.
What makes this even more frustrating is that Apple has known about the problem and has not done anything to fix it. (For my Apple readers, you can follow the discussions here, here and here).
All other operating systems are working fine except Mac OS X 10.5.3 and later.
We've tried everything possible to get this resolved – Contacted Apple Support, reviewed our WebDAV source code a thousand times and tested different usage scenarios. Finally, we decided to completely redesign our WebDAV software architecture to resolve this issue.
The good news is we have fixed this issue even though we didn't cause the problem. We are proud of this accomplishment because this proves our commitment to being an excellent service provider and striving to enhance our customer's experience.
Apparently these kind of nasty bugs have been a case with other service providers as well.
-Greg