Moving Entourage Mail to Mac Mail (folder, import, copy, power)

[cindycat]

I want to copy all my Entourage mail to the Mac mail system on my computer. I've done most of the folders (File-Import Mailboxes) but one large personal folder won't move completely. The system will tell me the action is complete but it isn't. This is the folder where I keep all the jokes, videos, PowerPoint things, etc.

Do I need to break it into several smaller folders before I can successfully move it?

Thanks.