Desktop theme goes to default at sporadic times

The desktop theme goes to default at sporadic times. My appearance preferences are set to Clear Looks (Gnome desktop). 99% of the time this doesn’t happen but while I’m working on something (next time I will note what I was working on) my appearance of my windows change colors to the default setting of sonar. After that happens I have to logout and log back in and the appearance is set back to Clear Looks. If I don’t logout and go to system/lookandfeel/appearances I automatically get logged out. Any idea what is causing this?