Launcher won't allow log-in

There are multiple accounts that use this machine. When attempting to switch users, Launcher sets the user to "Guest" and the switch user button stops working. "Play" button becomes grayed. All other functions of the Launcher are still functional. Reloading the Launcher does not correct the problem.

[17:16:22 INFO]: Minecraft Launcher 1.4.7 (through bootstrap 5) started on windows...
[17:16:22 INFO]: Current time is Jul 27, 2014 5:16:22 PM
[17:16:22 INFO]: System.getProperty('os.name') == 'Windows 8.1'
[17:16:22 INFO]: System.getProperty('os.version') == '6.3'
[17:16:22 INFO]: System.getProperty('os.arch') == 'x86'
[17:16:22 INFO]: System.getProperty('java.version') == '1.7.0_65'
[17:16:22 INFO]: System.getProperty('java.vendor') == 'Oracle Corporation'
[17:16:22 INFO]: System.getProperty('sun.arch.data.model') == '32'
[17:16:22 INFO]: JFX has been detected & successfully loaded
[17:16:23 INFO]: Refreshing local version list...
[17:16:23 INFO]: Refreshing remote version list...
[17:16:24 INFO]: Refresh complete.
[17:16:24 INFO]: Loaded 2 profile(s); selected 'LexiWostrel'