Take the ram out of the slot and "reseat" it (reinstall it).  Did you drop your notebook?  Just curious as to why you'd need to reseat it. 

Is this a hardware problem?  Is there anything I can do to change the memory settings other than to open the laptop?

 

The problem occurred once before about a month ago.  On a restart a week later, the system changed itself back to 1 GB.  However, it recurred again today, and will not reset to 1GB after 3 restarts.

Sometimes the memory comes loose and needs to be reseated.  This makes sure that the connections between the memory sticks and the edge connector on the motherboard has good contact.