File isn't a valid 'xx' file

Hi,

I have recently upgraded an old installation of CMSB to 2.11 so the Save & Copy plugin can be used.

However, when trying to 'save and copy' a record, I receive the following error:

Error:
Warning copy(picture.gif): failed to open stream. No such file or directory in /path/to/root/cmsAdmin/lib/upload_functions.php on line 84

[repeated for each upload in the record]

File 'filename.gif' isn't a valid 'gif' file.<br/>
[repeated for each upload in record, inc .jpg and .png]

The files do indeed exist in /path/to/root/cmsAdmin/uploads and load fine in browser.

In general settings all looks like it should:

Program dir: /path/to/root/cmsAdmin/
Website root: /path/to/root/
Upload dir: /path/to/root/cmsAdmin/uploads/
upload folder url: /cmsAdmin/uploads/


Any idea what would cause the 'isn't a valid 'gif' [png/jpg] file? I've tried reuploading the file and no difference.

Thanks!
Rob