Printing on a KM 6000L with an embedded rip.

We have an issue that occurs often, but not all the time. When ripping files.
When you process and hold a job and look at the preview it hasn't ripped the job in the centre of the sheet, so some of the image (usually the bleed and crops) are missing because they are hanging off the sheet.

The files have been tested on another RIP and the problem doesn't occur.
The RIP has had all the most recent patches on it and it doesn't seem to have solved the problem.

Has anyone got any suggestions or had this problem themselves.

Thanks