It seems to me the card & host device compatibility problem that causes data/file corruption. You should try another microSD (or technically microSDHC card if more than 2GB) card from another maker and see if the same problem exists with the phone, or check with any software driver patch available from the mobile phone maker.

BTW, Sandisk, as the most well known memory card provider, has the most fake cards in the market as well, mostly in Asia.