interrupted export of photos / odd error msg

I'm trying to export my entire photo library to a Windows laptop. I've got file sharing set up and a destination in mind (the Pictures folder on my Dell Vostro).

I open iPhoto, go to the Photos view and select all using CMD-A. Then I hit export, chose "original" format, and select the destination.

All seems to be going well; then, about halfway through the process (I have maybe 3,000 photos), I get a message that "volumes/users/My Name could not be exported" and the exporting freezes.

What causes this glitch and/or how do I get around it?