I'm having a very odd problem. I have a WD MyBook ES that has both USB and eSata ports. I have 2 partitions on it- 1 is HFS+ and the other is FAT32. Both work fine with USB. With the ExpressCard however, I encounter a problem with the HFS+ partition. Both show up under Leopard, but after I copy 1 or 2 files to the HFS+ partition I get either a "Filename too long" error or an "unexpected error" -50 error code on any other operation. From that point forward, the partition acts as if its read-only, but doesn't show that in any of the permissions. All write operations fail after this. However, the Fat32 partition continues to work just fine, and does not appear to suffer from the same problems. It seems I can copy files to and from it all day without problems. Both are on the same drive, going across the same controller. The card is a T-EC2R made by ONNTO (onnto.com). Its essentially a reference implementation of the sil3132 expresscard eSata 2. In fact, I've flashed the reference bios to try to troubleshoot the problem, and I'm using their drivers since ONNTO does not provide mac drivers for this card. The short story is that I ordered the T-EC2S, which does have drivers for OS X, but they shipped me the T-EC2R. When I realized it was a reference design, I just used the drivers from Silicon Image. I've tried a few things. After I noticed this problem, I tried flashing the non-RAID bios onto the card, and this worked ok. The card functions under bootcamp and Windows just fine, and it appears as though everything works initially under OS X. I just don't understand why HFS+ is failing and Fat32 is succeeding. I've run a disk check on the drive and HFS+ checks out just fine. All I can imagine is that Fat32 is getting silently corrupted if indeed there is a problem. I tried a verify on the disk, and it came back ok. So I tried a repair just for kicks, and it fails to unmount the drive. No applications have the drive open. Using Fat32 really isn't an option because I anticipate having files over the 4 gig limits with video production. Also, it seems the time machine doesn't like Fat32....figures. At this point, I'd just like to find a good card that works with a MacBook Pro running Leopard. But if I could fix this situation I'd be fine with it. Before someone screams firewire 800, I have an original intel MacBook Pro (1.0 rev) that has Firewire 400. I use the system for recording and push about 12 channels of 24 bit/48khz through the firewire port now. I will admit that I have not tried recording over USB to the MyBook because I don't trust that its fast enough to handle that amount of data. It might be, but nothing sucks more than recording a take and discovering there was problem. Finally, i had tested this card before the Leopard upgrade and I thought it was working fine in OS X. I had not done extensive testing with it though because I've been doing the recording under Windows. I've seen others talk about the Silicon Image drivers working fine with Leopard betas. So I'm at a loss.