Generally, that's not a good sign. Random characters are usually indicative of random data - which points to some form of corruption (either of the file(s) which control the attributes of the drive, or of the drive itself). You get a similar effect, for example, on corrupt CD-ROMs, where the names of folders can appear as random strings of characters and symbols.
Use disk utility to verify the disk (and verify the permissions, although that's unlikely to be the cause of the problem)