External Physical Volume OS X Extended

Something is very wrong with my MacBook Pro with solid state drive. The fan keeps running as if it is processing something. The hard drive shows that it has 54G available and then it keeps going down, now at 35.1G! And when I access the Disk Utility it shows 4 Installer Disk Images, all with 41MB called Disk Image External Physical Volume OS X Extended. At times, when this was happening, all apps crashed because the system had no available disk space. If I shut it down, and bring it back up it has 54G again. Argh! Has anyone else had to deal with this insanity?