I'm experiencing the same issue on a 2010 MB Pro w/ 8GB RAM and 2.66GHz i7. I *think* that it was happening before I upgraded to Yosemite, but not often enough to be concerning. Now it happens once every couple of days.
My symptoms are as follows: I'll be working away on something, then the screen goes black for a few seconds before I hear the disk restart, and then the gray panic screen comes up. There is never a panic log. When I inspect /var/log/system.log, I find
I don't see anything especially sinister in the logs leading up to that. Here are a few lines just before where I think it rebooted:
May 2 16:14:45 MacBook-Pro.local SophosSXLD[360]: 20150502 231445.735 P 360 T 2203 ------ 2 - Warning: EARLY TIMEOUT: dns context 0 has 13669 ms before it should time out\n
May 2 16:14:46 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47630]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:14:46 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:14:48 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47631]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:14:48 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:14:50 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47632]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:14:50 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:14:52 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47633]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:14:52 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:14:54 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47634]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:14:54 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:14:56 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47635]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:14:56 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:14:58 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47636]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:14:58 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:15:00 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47637]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:15:00 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:15:02 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47638]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:15:02 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:15:04 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47639]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:15:04 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:15:06 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47640]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:15:06 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:15:08 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47641]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:15:08 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:15:10 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD[47642]): Service could not initialize: Unable to set current working directory. error=2, path=/Applications/SafeConnect.app/Contents/MacOS/: 14D136: xpcproxy + 12761 [1285][E34BADE4-4125-3886-AA5B-08E47BD0E884]: 0x2
May 2 16:15:10 MacBook-Pro com.apple.xpc.launchd[1] (scManagerD): Service only ran for 0 seconds. Pushing respawn out by 2 seconds.
May 2 16:15:56 localhost bootlog[0]: BOOT_TIME 1430608556 0
Hope that someone figures this out soon.