After updating to 4.0.8 on our SG560 a few weeks ago we've had infrequent, intermittent network slowdowns and outages. I had chalked it up to ISP problems (Cox Business Fibre), but after digging further in the logs it appeared their Cisco router (2600 series--old, discontinued hardware) was seeing lots of speed negotiation resets from the SG560, which is connected on Port B and was set to auto-negotiate. This morning I forced the SG560 Port B to 100Mbit full duplex and so far we're not seeing any more resets.
Thought I'd share this in case someone else is having similar symptoms.
Thanks for sharing that Terry...it is a useful tip