I would like to share my experiences with occasional crashes I have experienced on 3 different machines once I had upgraded to C7.0.5. ALl 3 machines are from Dell (T5500 and 3500 Workstations, Inspiron I7 Notebook).
Crashes and also other really strange symtpoms started after I had upgraded to C7.0.5. I had gotten into the habit of always making sure to use the latest Video Card Drivers installed (all NVidia Cards) directly from the manufacturer (NVidia).
When the crashes started, I went back to the Dell Website and downloaded the last Dell-approved video card drivers, which were many Version numbers behind the one provided by NVidia. After I installed those older driver Versions from Dell, all crashes and other new symproms went away. I have not had a single crash since then.
May be this information is hepful to others who experience trouble with C7.0.5.