i put the sd card from my sensation 4g into my computers card reader. in windows 7 i went to start > rightclick "computer" and click manage. i then clicked on "Disk Management" to see what type of condition the sd card was in. it said it was a RAW disk. i started to think and then decided to try a chkdsk to see if it fixes it. to do that i just clicked START > RUN (or START > type in RUN and click the run shortcut) and type in CMD in the box then click ok. now in the command prompt type in CHKDSK X: /R then press the enter key (NOTE: X represents the drive letter). wait for it to do its thing and it should fix this problem.
i am not sure if it will fix it for all cases but atleast it worked for me.