Randomly appearing control characters in text files

Hi,

From some time, we have noticed that our ascii files have started corrupting due to the presence of some random control characters (^@, ^M, ^H, ^D). The characters appear randomly on any file after the process that creates the file finishes. If we rerun the process, the files re creates perfectly without problems.

The appear on any file randomly. Their location in the file is also random. We tried a reboot of the server (AIX 5. something), but the problem still persists. We found some bad blocks on disk during reboot and then we did a restore from backup.

The problem still persists.

Thanks
Aakash