Cannot connect to fulfillment server on ADE/Cannot connect to internet to deauthorise

Help please - I have tried everything I can. ADE just stopped working for me. I cannot return library books or transfer them - I get "cannot connect to fulfillment server on ADE" message. I have tried uninstalling and reinstaling several times. Doesn't help. Programme running incredibly slowly. I cannot deauthorise my computer in an attempt to completely start again - tells me its not connected to the internet when I try!

My internet is working fine - so that's not the issue. ADE just incredibly slow and not commuminating with internet somehow?

Any suggestions please? In idiot speak - I am not computer literate (just disconnected from my Public Library.....)