Unable to change user settings

Hi, I'm unable to change user settings, such as name, email, bio and other profile information -- even my own, and I'm the admin! Please help me figure out why.

Active Plugins include:
Akismet
Conditional Captcha
CoursePress Pro
iThemes Security
MarketPress
T(-) Countdown
WPMU DEV Dashboard
WP Super Cache

Please note that all of these same plugins, except CoursePress Pro and MarketPress are active on 2 of my other sites, and I do not have this problem elsewhere.

Thank you.