What could cause multiple ephemeral ports open to SYN back to a switch ?

Situation: I have two identical Netgear GS748Tv3 switches in the same location connected to each other through one port. As of three days both stopped allowing management though the HTTP interface. After pulling the power and restarting I have access to the HTTP interface. One of the switches is behaving slugglishly at responding to HTTP to manage it through its interface. This has been occuring to three additional switches of the same type in our domain within the last month. I know it is possible for switches to go bad, and capcitors to fail, but for all five to go bad within a month of each other and three within a week seems unlikely.
 
So I began a capture of what was occuring from my management station to the switch and of the backbone traffic to the switches. The only thing that seems to be out of the ordinary on the one sluggish switch is that when I open the HTTP management page it is opening additional ephemeral ports in sequence to send SYN messages and getting no response before finally cycling back to the orginal ephemeral port that began opening the page and finally sending an ACK message. This has been checked from multiple PCs.
 
Questions: Has anyone experience this before? If they have what is/was the common cause? Could this be an electrical issue causing a bit shift? Or could there be something else at play like HTTP pipelining gone arry or TCP SYN attack? or are we most likely experiencing devices failing around the same time?