I didn't see event ID 2017 in any of the event logs ( in fact it's curious that no errors or warnings are ever logged in association with this error. However, I tested Shadardrin's suggestion anyway, setting the registry to disable SMB2, but it does not correct the problem. Next, I tried Luca's suggestion and installed Teracopy. This utility effectively replaces Explorer's copy/paste functionality. Lo and behold, the folder copies over perfectly. My conclusion at this time is that it's Microsoft's bug. [Sigh] Changing the NIC, cables & switch had no effect, and it's only reproducible on Windows 7 (Don't know about Vista. Like many, I abandoned Vista after a couple days of it refusing to install the software I wanted to run.) I'm not going to burn any more time on this unless the Teracopy workaround fails. I'll check back on this thread periodically to see if anyone finds a concrete solution ( I still consider this question "unanswered") Thanks to everyone for their input and suggestions, especially Luca and to Code Sector for coming up with a utility that can do what Win 7 can't -- copy/paste a folder! Ken.C