You may have a corrupted file system, probably caused by not shutting Linux down properly before turning off the power or resetting. You need to use a recent shutdown program to do this—for example, the one included in the util-linux package, available on sunsite and tsx-11.

If you're lucky, the program fsck (or e2fsck or xfsck as appropriate if you don't have the automatic fsck front-end) will be able to repair your file system. If you're unlucky, the file system is trashed, and you'll have to re-initialize it with mkfs (or mke2fs, mkxfs, etc.), and restore from a backup.

NB: don't try to check a file system that's mounted read/write—this includes the root partition, if you don't see

   VFS: mounted root ... read-only

at boot time.