Like SpeedingWheels said, hit the menu key on your phone, tap "manage apps" then hit the "media area" tab at the top of the screen. This will show you all of the apps that are available to be installed in the media area (what we're used to hearing as the "move to SD" area).
The Bionic has a known issue right now, where apps installed in this "media area" are not stable, so you DO NOT WANT any apps to install in the media area. Any apps that have a check mark on this screen need to be moved back to the phone's internal app storage area. (There is 4GB of internal memory in the Bionic that is reserved EXCLUSIVELY for apps, so don't worry about running out of space for your apps - for now) Tap on any apps that are checked and then tap "move to phone". Problem solved, for now. (update fix supposedly coming in Nov.)
Also, be aware that some developers have created their apps to automatically "install to SD card". This will cause them to install to the Bionic's media area automatically. Get in the habit of doing the "menu >manage apps > media area" check after you install a new app - just to make sure it hasn't auto-installed there. I believe that's exactly what is happening with the Droid Forums app.