ActionReplay Max for the PS2 can be useful for backing up your game saves, but it also contains gotchas that can destroy them as well. Here's a quick guide to the gotchas and how to work around them.
Failure to Read While Restoring: Sometimes the MaxMemory software will report an error while trying to copy (or uncompress) a game save from the ActionReplay flash drive to a standard PS2 memory card. In fact, it will sometimes happen multiple times on a single save file. This may give you the idea that the save is corrupt on the flash drive. Fear not! Often ActionReplay has trouble reading its own flash drive. Retry the operation several times, and reset the PS2 at least once and try several more times, before giving up. One of my saves refused to be copied five or six times before finally succeeding.
Failure to Write While Restoring: Sometimes the MaxMemory software will corrupt the data on the standard PS2 memory card it's writing to, resulting in a partially or wholly unusable memory card. The PS2 browser cannot be used to reformat the card. The only way to recover use of the card is to reformat it using the MaxMemory software. Once reformatted, it can be used again, but all of the saves that were on the card are gone. I strongly recommend restoring saves only to a memory card that has nothing else on it.
Incompatible With Other ActionReplay Hardware: The ActionReplay MaxMemory software can neither read from nor write to the ActionReplay MaxMemory 64MB memory card. It only works with standard 8MB memory cards and the 64MB USB flash drive that comes with the MaxMemory software.