Apologies if this has been outlined already, but I noticed whenever any mage in my party casts Spirit Armor (the one that deals damage when it expires), 'I cannot save at this time' I also get 'You cannot rest at this time'. The only solution I have found, is to either:
1. Dispel the buff and save/rest or 2. Wait until the buff expires (minimize until I hear my buffed character wince from damage being dealt to him/her) then save/rest.
I just thought people might like to know. I hope this helps at least someone.