MyDVD captures always stop after 1 min

Just tried to capture some video via firewire on a new dual core
desktop system with loads of RAM & HD space with the supplied My DVD LE
software. I was familiar with the processs from an earlier MyDVD
version (4.5?) I'd used on my old computer. But now capture always
stops about a minute in, at around 200 MB when capturing DV qualiry or
65 MB when usung its highest quality MPEG setting, asking me what to
save the file as. The fact that these file sizes are very different
tells me it isn't a space issue (I have specified a partition for the
temp files and captures with oodles of space in any case), the drives
are the fastest I've ever owned and happily capture DV quality .avi
from WinDV with no dropped frames, so I very much doubt it's an issue
of drive speed. Happens when Set Capture Length box is not ticked, or
ticked with a length specified.