I've noticed lately at least a couple of jobs featured in my "Looking for a job" sidebar box link through to invalid/expired/missing jobs. For example, I currently have this link:
Which shows a page saying
Job Not Found
Sorry, we couldn’t locate that job listing. It might have expired or been removed.
If you feel something is missing that should be here, please contact us.
as at 28th January 2015.
Is this just a caching issue - perhaps jobs have been removed recently and the ads haven't refreshed?