Grey Screen with restart error message

[bobmobile]

Hello all,
I've seen this covered before with different causes, but while working twice in the last month I've had a grey screen appear with an error message saying I need to restart on my 2011 iMac. Here's what I found in the crash report. Any ideas.
Thanks in advance.
Bob

Wed Dec 11 11:56:54 2013
panic(cpu 1 caller 0xffffff80002c4794): Kernel trap at 0xffffff800057ef68, type 14=page fault, registers:
CR0: 0x000000008001003b, CR2: 0x00000001ffffffcc, CR3: 0x0000000027e60000, CR4: 0x0000000000000660
RAX: 0x00000001ffffff80, RBX: 0xffffff80005672ef, RCX: 0x0000000000000000, RDX: 0x0000000000000000
RSP: 0xffffff81c808be10, RBP: 0xffffff81c808be30, RSI: 0x0000000000000001, RDI: 0xffffff8023c07000
R8: 0x0000000000000002, R9: 0x00001eb95b2b83b4, R10: 0x0000000000000000, R11: 0xffffff80002dad60
R12: 0xffffff80211e5980, R13: 0xffffff8023c93420, R14: 0x0000000000000001, R15: 0xffffff8023c07000
RFL: 0x0000000000010246, RIP: 0xffffff800057ef68, CS: 0x0000000000000008, SS: 0x0000000000000010
CR2: 0x00000001ffffffcc, Error code: 0x0000000000000000, Faulting CPU: 0x1

Backtrace (CPU 1), Frame : Return Address
0xffffff81c808bac0 : 0xffffff8000220792
0xffffff81c808bb40 : 0xffffff80002c4794
0xffffff81c808bcf0 : 0xffffff80002da55d
0xffffff81c808bd10 : 0xffffff800057ef68
0xffffff81c808be30 : 0xffffff80005672ef
0xffffff81c808be60 : 0xffffff8000563aa9
0xffffff81c808bf70 : 0xffffff8000555fe9
0xffffff81c808bfb0 : 0xffffff8000820057

BSD process name corresponding to current thread: Fetch

Mac OS version:
11G63

Kernel version:
Darwin Kernel Version 11.4.2: Thu Aug 23 16:25:48 PDT 2012; root:xnu-1699.32.7~1/RELEASE_X86_64
Kernel UUID: FF3BB088-60A4-349C-92EA-CA649C698CE5
System model name: iMac10,1 (Mac-F2268CC8)

System uptime in nanoseconds: 33781445204455
last loaded kext at 69714121410: com.apple.filesystems.afpfs 9.8.1 (addr 0xffffff7f8264b000, size 356352)
last unloaded kext at 145906527433: com.apple.driver.StorageLynx 3.0.6 (addr 0xffffff7f82230000, size 8192)
loaded kexts:
com.apple.filesystems.afpfs 9.8.1
com.apple.nke.asp_tcp 6.0.1
com.apple.filesystems.smbfs 1.7.2
com.apple.driver.AppleHWSensor 1.9.5d0
com.apple.driver.AudioAUUC 1.59
com.apple.driver.AppleMikeyHIDDriver 122
com.apple.iokit.IOUserEthernet 1.0.0d1
com.apple.driver.AppleMikeyDriver 2.2.5a5
com.apple.driver.AppleHDA 2.2.5a5
com.apple.iokit.IOBluetoothSerialManager 4.0.8f17
com.apple.Dont_Steal_Mac_OS_X 7.0.0
com.apple.driver.AudioIPCDriver 1.2.3
com.apple.driver.ApplePolicyControl 3.1.33
com.apple.driver.AppleUpstreamUserClient 3.5.9
com.apple.driver.AGPM 100.12.75
com.apple.driver.AppleLPC 1.6.0
com.apple.filesystems.autofs 3.0
com.apple.driver.ACPI_SMC_PlatformPlugin 5.0.0d8
com.apple.driver.AppleBacklight 170.2.2
com.apple.driver.AppleMCCSControl 1.0.33
com.apple.GeForce 7.3.2
com.apple.driver.BroadcomUSBBluetoothHCIController 4.0.8f17
com.apple.driver.Oxford_Semi 3.0.6
com.apple.AppleFSCompression.AppleFSCompressionTypeDataless 1.0.0d1
com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0d1
com.apple.BootCache 33
com.apple.driver.AppleIRController 312
com.apple.driver.AppleUSBCardReader 3.0.6
com.apple.iokit.SCSITaskUserClient 3.2.1
com.apple.iokit.IOAHCISerialATAPI 2.0.3
com.apple.driver.XsanFilter 404
com.apple.iokit.IOAHCIBlockStorage 2.1.0
com.apple.driver.AppleRTC 1.5
com.apple.driver.AppleFWOHCI 4.9.0
com.apple.driver.AppleAHCIPort 2.3.1
com.apple.driver.AppleUSBOHCI 5.1.0
com.apple.driver.AirPort.Atheros40 505.67.1
com.apple.nvenet 2.0.17
com.apple.driver.AppleUSBHub 5.1.0
com.apple.driver.AppleEFINVRAM 1.6.1
com.apple.driver.AppleUSBEHCI 5.1.0
com.apple.driver.AppleHPET 1.7
com.apple.driver.AppleACPIButtons 1.5
com.apple.driver.AppleSMBIOS 1.9
com.apple.driver.AppleACPIEC 1.5
com.apple.driver.AppleAPIC 1.6
com.apple.driver.AppleIntelCPUPowerManagementClient 195.0.0
com.apple.nke.applicationfirewall 3.2.30
com.apple.security.quarantine 1.4
com.apple.security.TMSafetyNet 8
com.apple.driver.AppleIntelCPUPowerManagement 195.0.0
com.apple.security.SecureRemotePassword 1.0
com.apple.driver.DspFuncLib 2.2.5a5
com.apple.iokit.IOSurface 80.0.2
com.apple.iokit.IOSerialFamily 10.0.5
com.apple.iokit.IOAudioFamily 1.8.6fc18
com.apple.kext.OSvKernDSPLib 1.3
com.apple.kext.triggers 1.0
com.apple.iokit.IOFireWireIP 2.2.5
com.apple.driver.AppleSMC 3.1.3d10
com.apple.driver.IOPlatformPluginLegacy 5.0.0d8
com.apple.driver.IOPlatformPluginFamily 5.1.1d6
com.apple.driver.AppleSMBusPCI 1.0.10d0
com.apple.driver.AppleHDAController 2.2.5a5
com.apple.iokit.IOHDAFamily 2.2.5a5
com.apple.driver.AppleGraphicsControl 3.1.33
com.apple.driver.AppleBacklightExpert 1.0.4
com.apple.driver.AppleSMBusController 1.0.10d0
com.apple.nvidia.nv50hal 7.3.2
com.apple.NVDAResman 7.3.2
com.apple.iokit.IONDRVSupport 2.3.4
com.apple.iokit.IOGraphicsFamily 2.3.4
com.apple.driver.AppleUSBBluetoothHCIController 4.0.8f17
com.apple.iokit.IOBluetoothFamily 4.0.8f17
com.apple.driver.AppleUSBHIDKeyboard 160.7
com.apple.driver.AppleHIDKeyboard 160.7
com.apple.iokit.IOFireWireSerialBusProtocolTransport 2.1.0
com.apple.iokit.IOFireWireSBP2 4.2.0
com.apple.driver.AppleUSBHIDMouse 175.9
com.apple.driver.AppleHIDMouse 175.9
com.apple.iokit.IOUSBHIDDriver 5.0.0
com.apple.iokit.IOSCSIBlockCommandsDevice 3.2.1
com.apple.iokit.IOUSBMassStorageClass 3.0.3
com.apple.iokit.IOSCSIMultimediaCommandsDevice 3.2.1
com.apple.iokit.IOBDStorageFamily 1.7
com.apple.iokit.IODVDStorageFamily 1.7.1
com.apple.iokit.IOCDStorageFamily 1.7.1
com.apple.driver.AppleUSBMergeNub 5.1.0
com.apple.driver.AppleUSBComposite 5.0.0
com.apple.iokit.IOSCSIArchitectureModelFamily 3.2.1
com.apple.iokit.IOFireWireFamily 4.4.8
com.apple.iokit.IOAHCIFamily 2.0.8
com.apple.iokit.IO80211Family 420.3
com.apple.iokit.IONetworkingFamily 2.1
com.apple.driver.NVSMU 2.2.9
com.apple.iokit.IOUSBUserClient 5.0.0
com.apple.iokit.IOUSBFamily 5.1.0
com.apple.iokit.IOHIDFamily 1.7.1
com.apple.driver.AppleEFIRuntime 1.6.1
com.apple.iokit.IOSMBusFamily 1.1
com.apple.security.sandbox 177.11
com.apple.kext.AppleMatch 1.0.0d1
com.apple.driver.DiskImages 331.7
com.apple.iokit.IOStorageFamily 1.7.2
com.apple.driver.AppleKeyStore 28.18
com.apple.driver.AppleACPIPlatform 1.5
com.apple.iokit.IOPCIFamily 2.7
com.apple.iokit.IOACPIFamily 1.4