Dear Warren and Tsjerk, Thank you for responding so quickly to my question. Im not sure what the underlying OpenGL graphics are on my computer. However, I have changed nothing on my computer. I can open and look at both versions of the pdb file in PyMOL, look at them side-by-side, and they respond very differently. The problem is reproducible. I dont how to write scripts yet, but I can give you a list of what I do. I have attached the two files: Old1FOD.pdb ( the file that is easy to use) and 1FOD.pdb (the most recent version of the file from RCSB that is difficult to use). 1) I double click on the pdb file and it opens automatically in PyMOL 2) In the Menu: Display: Sequence: Sequence Mode: Residues 3) Highlight residue #1 4) (sele) choose show sticks 5) (sele) choose Action: Find: Polar Contacts: To any atoms 6) (sele) choose Action: Orient or Zoom If I use the older version of the pdb file, the residue is zoomed in and I can easily turn the whole molecule around 360 degrees. If I use the newer version of the pdb file, the residue is zoomed out I cannot zoom in unless I use the left mouse button, and I cannot turn the molecule around 360 degrees. Thank you for your assistance, Nicole Lewis-Rogers
--------------------------------- Looking for a deal? Find great prices on flights and hotels with Yahoo! FareChase.