memory over load?

Hi Lynn,

You are posting to the Epi Special Interest Group list in R (R-Sig-Epi). 
  This is a list to post specific question about epidemiological 
analysis using R.  If you have a general question about using R, you 
should subscribe to the general R-Help list.  For a general a 
introduction about the different R-lists, please visit this website 
http://www.r-project.org/mail.html

Type ?gc into the R console-> hit Enter and you will see the answer to 
your second question.

I hope this helps,

Francisco