charmm and SGIs - charmm newsgroup?

 I have been getting a problem with the commercial version of charmm
 running on a Silicon Graphics personal iris 4D/20 and I wonder if
 anyone else has experienced a similar problem. The system crashes if
 I try to use tar when charmm is running in background. Any ideas?
 Also, does anyone know the addresses for charmm or amber discussion
 groups? All contributions gratefully received.
 Nick Tomkinson