Plug-in deactivating automatically

We installed the User Photo plug-in on our “About Us” page on our WordPress website. For some unidentifiable reason the plug-in keeps deactivating without cause (making our photos not show up on the website). We keep activating it, it works for a little while, and then it automatically deactivates again. What’s going on? We’re worried that the plug-in doesn’t work properly with the newest version of WordPress. Or maybe one of our other plug-ins is negatively interacting with the User Photo plug-in? We’re going to use Gravatar to help deal with this issue (i.e., our photos will revert to Avatars if the plug-in deactivates) but we’d still like to solve this problem

http://wordpress.org/extend/plugins/user-photo/