We have no issues reported with the service and all our internal tests are green. Is it a specific set of documents you are trying to download or random?
I think it must be something at this end. After the problems with downloading documents, I started having issues with the Beta Site and also with CHD. Strangely though, I had no problems at all with any other website or service.
Resorted to a reboot and all seems ok now, so presume some kind of routing problem.