Problem importing media

I seem to be having a problem with importing the media from my Joomla site.
If I skip the media, everything else seems to import fine, but if I include the media (which I would like), then I seem to get no media whatsoever, and I only get 173 categories, and no posts etc. When I tried doing it all as pages, I got 50000 or so pages, mainly all blank entries when I had a look in the database, and I just get a generic “internal server error” in the browser.
I’m not sure if the problem is because the two sites are not on the same host (or even the same geographical area), directory permissions, or memory, or what. Or is there some other way I could move the media first ?

Setup is:
Joomla 1.5 on a remote Linux host, with K2
Wordpress 3.4 in IIS on Windows Server 2008r2
Using the FG plugin premium version, with the K2 addon.

http://ww.wp.xz.cn/extend/plugins/fg-joomla-to-wordpress/