Ark complains about a lack of space.

[Teunis]

Sometimes I get an error opening an archive via Ark,
These are multi part rar archives from a news server, right clicking to open 'here' regularly results in the message there is not enough space.
Yet the disk shows plenty of space in /home and also in /root.
Opening the first part in Ark works fine but I get the same message when exporting the file in question, not enough space.