Occasional problems reading or writing to the memory card.

Occasionally, my D70 will give a "CHR" or Format in place of the number of pictures left to be taken. sometimes reinserting the memory card will fix it. Sometimes, after taking several pictures, it will give this message and the pictures will be lost. Often it is when I am shooting outside or the temperature has changed.

Is there a fix? Will a cleaning of the pins resolve my issue?