What are you doing when you get an unresponsive error message? Listing? Searching?
Try an alternative link to rule out a bad link.
Try another browser to rule out a browser issue.
Try temporarily disabling your add-ons such as ad blockers to rule out a conflict.
Anything odd about your network? Using a VPN or hotspot? Custom firewall? Privacy software such as Disconnect or Ghostery?
Try another device to rule out a device issue.
Try another network to rule out a network issue.