Mine (or more accurately a customer's) is somewhat flaky as well.
I remote into their SBS server to do my work and have found recently a lot of DNS-320L web GUI freezing was solved by a power cycle of the unit. However the problems didn't stop there. When I was able to resume backups with Acronis Backup & Recovery SBS Edition, after a while the server (SBS2011) will lose the LAN connection to the DNS-320L and the backup obviously fails.