A problem with my new card reader

I work as an assistant for a fashion photographer
and we recently bought a new card reader.
When we first bought it, it worked on my macbook pro,
but when we tried to use it on our powerbook g4 at a shoot
it wasn't able to transfer the data over. it would freeze and
we had to hold the power button down to shut the laptop off.

Is there a problem with the computer or the card reader?
if there is anyone who knows a good CF card reader that is
compatible with a mac please share info~

HELP
or my boss will fire me~

i had similar problem with my old sandisk 6in1 reader, so bought a sandisk firewire CF reader and it's been faultless. Quick too..