I did a search and this is the closest I found to someone having the same problem, though I am not sure it is exact as it concerns the 4TB edition, not the 1TB edition I have.
My setup: A MacBook Pro connecting wirelessly to a Belkin N+ Access Point that has a wired connection to my WD 1TB MyBook World Edition. I purchased the MBWE about 7 or 8 months ago and it had been working great. TimeMachine always backed up and I could always mount the Public or Download folder from the left pane of the Mac Finder with a click. I loved it.
About 2 months ago I started getting intermittent failures from TimeMachine saying it could not complete the backup. Since I was not changing that much data and I was traveling a lot for work I didn’t take the time to really see what was happening and upon checking my TimeMachine backups it was working often enough that I was OK. I also keep a second USB drive handy with a duplicate of media and such so losing the 1TB MBWE wasn’t going to kill me.
Fast forward to today and I still get the intermittent failures from TimeMachine. In addition I tried to click MyBookWorld in the left Finder pane and it just sits there saying “connecting”. It never stops and it never actually connects. If I use the Go->Connect Server… route I have different outcomes.
If I afp://mybookworld.local/ it will pop up and ask for username and pw. If I use admin or the user I created to match my MacBookPro account I get the same result. It will then ask me which volume I want to mount and when I choose Public it just sits there forever saying “connecting” and never does. Similar to clicking it in the Finder pane.
If I smb://mybookworld.local/ it will pop up and ask for username and pw. If I use admin or the user I created it accepts. It will then ask me which volume I want to mount. When I choose Public, it mounts successfully! OK, so now when I look in my Finder, the left pane now lists mybookworld.local (mounted via smb), MyBookWorld (which doesn’t really work), and MyBookWorld-Backup (which I never touch).
It seems to me the problem is specific to afp access and I have not changed anything on the MBWE settings. I can access the MBWE configuration via Firefox or Safari. When I check the settings afp is still enabled as well as nfs, etc. I don’t use Mionet, but that is at its defaults as is everything else with the exception of the user I created to match my MacBook Pro user account.
The drive is not full (far from it). I have used about 300 GB of the total capacity.
Any ideas out there as to why a) TimeMachine all of a sudden is intermittent and b) afp access does not work?