Problem booting from USB stick

[woody]

I have a Pogoplug that boots into ARM from a USB stick. This has been working well for some time. Now, I'm having the problem that the system hangs every so often and then refuses to boot up. If I remove the USB stick and mount it on another system, then unmount and put it back on the Pogoplug, it will boot up and run normally.

I'm guessing that this may mean that the USB stick is failing, but I can't tell for sure. Also, I can't figure out why mounting it on another system should make a difference. Does anybody have any ideas about this?