Couple of things come to my mind to test:

Did you try the file system check from a PC running Linux, either installed or Live-CD?
The version of fsck built into backupmenu and also Maemo are ancient, you will get better results from a PC.

Did you try to move the file, thereby not erasing the file completely but testing the read/write abilities of the rootfs.

You could also check the location of the real file Good luck!