Viewer 2 was working fine. I installed Viewer 3, but when I start it, it crashes at detecting hardware or initializing VFS with this error, The instruction at "0x003e01ff" referenced memory at "0xa83eff7". The memory could not be "written" Now viewer 2 won't start either, giving this error, The instruction at "0x003e01ff" referenced memory at "0xb80304cf". The memory could not be "written" Win XP sp3 all current patches from windows update. nvidia 260GT, 4 G RAM, i7 quad CPU I installed the latest video driver, uninstalled all viewers, deleted program files caches files and app data files, rebooted, reinstalled the viewer, same results. I even did a scan for viruses. What can I try next? EDIT: I seem to have fixed the problem by going into safe mode, uninstalling the nvidia graphics driver and SL viewer, rebooting and reinstalling the driver in custom mode, this time without installing nview option. Then I was able to install the SL viewer 3 and start it and login. Yay!