No issues here with 1GB RS-MMC on 770 either, based on almost a year usage history. But, after moving the same card to N800 I did have some corruption already once: This could be because I did remove/insert the card without powering down the N800. I think I read somewhere that N800 should handle "hot swap" of the memory card? (Of course not during data transfer, but when idle). I did not have virtual memory enabled, and it does not even seem possible on the external slot?