Only 100 kb/s transfer using My Passport Essential USB 2.0 with Mac?

I’m traveling through the moutains in northern India with a My Passport Essential (WDBABM7500ABK) and a MacBook Air (2010) running OS X 10.7  I’m trying to copy 50 Gb of photos onto the external drive, but after an  initial fast transfer of around 142 Mb, the transfer speed suddenly slows to aroun 100 kb per second.

The partition I’m tring to write to is FAT.  (The drive also has two other partitions - NTFS and Mac OS Extended).  I’m using the original short cable that came with the drive.  No USB hub or any other USB device in use.

I’ve used this drive in the past to back-up photos and got normal speeds.  I was wondering if upgrading from Mac OS X 10.6 to 10.7 might have caused some driver problem.  I’ve tried installing the  WD Macintosh +TURBO Drivers and have also used the WD Universal Firmware Updater for Mac , but those have not solved the problem.  I’ve also done a fast re-format of the FAT partition.

Any other suggestions?

Unfoutnately no suggestions but I have the same problem. Makes the thing really useless. I Have no mac but I updated the firmware too. Nothing happend. Im out of warranty, but would really like to repair it.