odd imac problem

I use a g drive thats hooked up with firewire 800 to my imac. The speeds have been fine until yesterday. It can take upto 4 hours to transfer a 10 gig file. Transfer from the drive to the computer is fine and as fast as it should be, but not the otherway around.
I've tried unplugging all other devices and leaving the drive only connected but still the problem exists. I even hooked up my g drive to my powerbook and had no problems. So basically it is ridiculously slow ONLY transferring from imac to g drive, yet completely fine from g drive to imac.


Any help is appreciated.

Thanks

 

yes, I hooked it up to firewire 400 ports and still the same thing.