I've been following this thread at Digital Spy with some interest, as I've had a similar problem when (effectively) recording two HD channels* simultaneously myself (as reported in previous postings). Is it sorted? Time will tell - but I think it's a problem with the box being unable to handle two HD feeds rather than a network issue.
*Yes, I know we only have the one HD channel, but if you record one and watch at the same time, you've got two tuners accessing the HD channel. If you want to record an HD programme and watch it, my advice is to actually watch it from your Recorded Programmes listing rather than as live TV. You'll only then have the one tuner accessing HD, and will still be able to pause or rewind without stretching the box to its limits. Well, that's my theory anyway!