I've continued to pursue the issue of R8 MATE 64bit failing to recognize my password when I launch apps such as Gdebi, apps that depend on password authorization to run. Even in Virtualbox, when I try to install the latest Extension Pack, the problem rears its ugly head and won't let me proceed. So far the best I've come up with is to make sure gksu-properties is set to *sudo* instead of *su*. However even with that set correctly the issue of my password being rejected as *incorrect*, even though it's not, remains the same - still not working..
I'll continue to monitor this forum and elsewhere for a possible solution to this problem. In the meanwhile I'll move on to less troublesome things and return for another look at R8 some other time..