Help Camera doesn't recognize SD card

[spaceman82]

I recently downloaded Astro File Manager to my Optimus One phone and used it to install an app via USB. The installation was successful and the app works fine, but when I try to use my camera, it now tells me to "Please insert a SD card." I'm also unable to view past photos through Gallery or to see enlarged thumbnails sent via message. The SD card seems to be working fine for everything else except pictures. Any ideas on how to fix this problem and get my camera working again?