Windows registry problem

I have just inserted a new PC133 128mb memory chip into a PC no problems, then i tried to run scan disk and disk defrag only to be told there were errors that needed fixing so i persisted only until scan disk froze up.
Restarted the PC, only to be greeted by Windows can not access the registry due to insufficient memory.
Every time i restart the memory is not counted/checked i get as far as my background screen but nothing else boots ups.
Next steps ?