Odd client problem - backs up all files every night

[Angus Macdonald]

One of my clients has decided to back up all files every night, instead of
performing an incremental backup, so I have multiple identical copies of
ancient files and old versions of files are rapidly overwritten by multiple
copies of the current version.

I'm using the BA Client and all my client machines use a single policy. I've
checked that the default backup action in the client is incremental. Nothing
is logged to the error log that might suggest problems.

Is this a common problem and how can I fix it? I'm not that experienced with
TSM yet but we're running 5.3.3 on Windows 2003.

Thanks