Random chmod errors

[Peter Kratzer]

Hello friends,

some of my users are encountering random errors with the chmod command. The
errors are not exactly reproducible, so I cannot even narrow down the
circumstances of their occurrance.

What else do I know:
- Following message occurs: "chmod: changing permissions of
`filename' (requested: 0644, actual: 0444): Operation not permitted"
- Trying the same command with the same option again does the job as
expected
- In recursive calls (chmod -R) some of the files in the specified
directory do not have the requested permissions when the error occurs
- In some cases on single files the file's permission are actually changed
(the were quite surely different before, when the file was created) to the
requested value, even if the error message occurs
- The message differs from attempting to chmod files owned by different
users in the following part: "(requested: 0644, actual: 0444)"
- I have tried to find this message part in brackets ("requested: 0644,
actual: 0444") in the chmod.c source, but without success

At this point I have completely run out of ideas. Does anybody have any
idea where this problem comes from, what the reason might be?

I would appreciate any advice on this problem.

With best regards, and thanks in advance for your help,

Peter