I've got Scientific Linux 6.4 Installed (RHEL6.4) and am having trouble transferring to and from USB flash drives...
Transfer seems to hang multiple times during transfer to the device, and transfer from the device is slower than it should be (500kb/s), I think this is due to multiple hangs during this transfer too.
After quite a bit of googling I'm suspicious of this Memory Management Problem. I'm a bit dubious of the patch suggested as it may be worse than the original problem (see linked article in memory management problem).
Also, It seems this problem has been solved in a later kernel as show here. My current kernel version is 2.6.32-358.23.2.el6.x86_64. I'm not sure whether I should manually upgrade the kernel, having never done this before and I guess that a lot of the dependencies would also need upgrading from source too.
I didn't have this problem in version RHEL5 and rather than perform a fresh install, would like to fix this in 6.4. Let me know if you need more info.