Hi, any major reason you are still on OS X Leopard 10.5.8 ? Your MacBook Pro should accommodate at least Snow Leopard pretty easily, no? And it might be more mature in handling of corrupted cards. It might be too soon to upgrade to Lion, as it has caused some issues in PM which are AFAIK still being worked out (as Apple is quite known for silently dropping or changing system features software developers were using for years without so much prior notice in major releases), but being on OS two generations behind, when Snow Leopard alone costs just 29$, unless you depend on some other software which requires it, is not very sound. And Snow Leopard did have a lot of internal improvements over Leopard, more like a big service pack than a new release, polishing many things that were left unresolved in Leopard. Really, most of the added features in 10.6 over 10.5 were internal improvements. It might be quite possible that it will resolve your issue as well (not betting on it though
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So I suggest you to upgrade the system, and maybe later, when it is known to be stable and bug free, upgrade to Lion as well.
Second, why not buy bigger cards? And both CF and SDHC, as you can use both inside all of your cameras.
Yanking a card out of camera while it is still writing might result in ALL photos getting lost, it happened to me few times. It is a not very safe bet, that you will loose only the last few yet unwritten photos. At the very least the card might be getting degraded and damaged over time. The flash controller inside the card is doing pretty complex things with the bits, it's NEVER a good thing to remove a card that is still being written to. Once I couldn't recover such damaged card even with PhotoRescue. The flash controller is doing such things as wear levelling all the time, so yanking it out during write might really affect all contents of it, making them unrecoverable. With cards so cheap, just why risk it... Unless it's like in our newspaper where they were very keen on cheaping out on cards ;-)