First insert your pendrive,right click on MY COMPUTER, select PROPERTIES, select ADVANCED,select SETTING, SELECT ADVANCED, NOW select "CHANGE" and now u select the drive letter of ur pendrive above, then select the CUSTOMIZE SIZE tab here u give the amount regarding ur pendrive size in MB, AFTER GIVING THIS.....
COMPUTER NEEDS TO RESTART TO TAKE EFFECT.....THATS ALL
COMPUTER NEEDS TO RESTART TO TAKE EFFECT.....THATS ALL