IMovie: Can´t move events to external hard disk

Hi!

When trying to move events to an external harddisk, I get the following message:

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The file could not be copied:

/Users/***/Movies/iMovie Events.localized/Ny hendelse 11-01-12 – dag 4/iMovie Thumbnails/clip-2012-01-01 00;49;42

(-43)

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The harddisk is Mac OS Exended, and I do the moving inside the iMovie event library according to the Apple Support (http://support.apple.com/kb/HT1097).

Could anyone help me? I´m running out of disk space on my Mac....

Terese