Vista fail

I wanted to copy over my files from my old desktop computer to my (relatively) new laptop, so that I can start using the laptop as my main computer. The desktop is running XP; the laptop Vista. I shared a folder that I wanted to copy on the XP machine. I connected to that folder from the laptop. I started copying files.... most files copied fine, but a few of them caused an odd popup error "Destination Folder Access Denied". I can't tell what is different about those files. It's not their extension; other files with the same extension copied ok. Tried copying them from a command prompt; still got an Access Denied error. Tried copying them to a different shared folder on the desktop - then I am able to copy them to the laptop without getting the error. Makes no sense. Did a web-search, and found that other people have had the same problem, but there's no clear or simple explanation or solution.

So. I've decided to do the free upgrade to Win 7 on the laptop, before trying to copy any more files. Sayonara, Vista. Hopefully Windows 7 is better.