So here's the thing. On completely different hosts, installations, operating systems and versions of MySQL and PHP (and phpMyAdmin) (but always on a host I'm visiting over the Internet), I've found an interesting situation:
When I try to export a database table (MyISAM or InnoDB) which has "a lot" of data in it, using compression (gzip, zip, it doesn't matter), the file generated isn't complete.
I've put "a lot" in quotes, because it ranges from 1 000 rows to 30 000 rows, depending on the platform. It seems the actual amount is irrelevant.
I have worked around this problem by running mysqldump on the command line and then compressing the output, but I wanted to hear from the community whether this is a known issue, or if it has something to do with the crap bandwidth we have in South Africa, which was recently beaten by a carrier pigeon.