Hello kgupta_999,
Am an independent advisor and Microsoft Office User like you.
I usually experience what you are going through especially when i am saving documents in drive C [ my computer/local disk c]
From your narrative, you have moved between computers but seem that where you are saving your excel documents, it is violating one of the four conditions as stated by the notification popup when you save in the current folder and not on the desktop.
Create/move your folder to the [my documents] folder and try using it from there, see how it performs with your requirement. Ensure that it is not write protected.
let me know if this works for you going forward.
kind regards.