Googling, I'm seeing that error all over the place, but I'm not seeing any solutions.
My first thought is that maybe you replaced an old card with a 460, but didn't update the drivers to match?
Second, to get WUs for my new 460, I have to use an app_info.xml file. Are you using one? If so, are you sure it's correct?
Otherwise, what OS and BOINC version are you on?