I don't fully agree here that this is (always) caused by SL Viewer 3. This has been haunting me for three weeks, BTW, and I just solved it for myself without changing drivers.Only in my case it was Error 4, yet with an identical error message. Currently using Display Driver 280.26
If you are reading this error message closely, it says it lost connection to the (underlying) driver. This MAY also mean that the driver has gotten unresponsive due to other causes, essentially meaning whatever is going on pulled the carpet from under the feet of OpenGL and thus also the SL Viewer. In my case it always happened when doing stuff in Firefox 6/7. Like switching tabs or in one case simply clicking a link in Wikipedia. Screen goes black for a second, comes back, OpenGL error.
My solution is to set the TdrDelay variable to 0Ah (decimal 10) in the registy. This prevents Windows Vista and Windows 7 from prematurely resetting the display driver. Please look up the registry key "TdrDelay" in Google and how to set it if you're not experienced with the registry!
Copy and paste this into a text editor and save this as .reg file, for example "Delayfix.reg" and doubleclick the saved file.
Windows Registry Editor Version 5.00
Alternatively/additionally you may want to disable hardware acceleration in Firefox if you are suspecting that FF is causing the issue in your case. Hardware acceleration in Firefox has been troublesome for a while by now.
Hope that helps!