do not upgrade with web interface from the last version, there was a bug in the last version which could get you into troubles.
so please use the tftp recovery way.
plugin your cable into the wan port. plugoff the power cord. push the reset button, plugin power cord and hold the button for 10 seconds. 
then do "tftp -i 192.168.1.20 put RS.dd-wrt.bin"
no settings or activation will be lost