iMac keeps restarting every couple of minutes. Any ideas which software/hardware is the culprit? Backtrace suspected of leaking: (outstanding bytes: 1337520)
0xffffff801936bf56 
0xffffff80193b392d 
0xffffff80193a0cab 
0xffffff80193abcfd 
0xffffff80197c9475 
0xffffff801984bc56 

last loaded kext at 42505017282: com.symantec.kext.SymAPComm    12.7.1f4 (addr 0xffffff7f99ad5000, size 20480)
last unloaded kext at 104216742444: com.apple.iokit.IOAHCIPassThrough   1.0.3 (addr 0xffffff7f9ac5b000, size 36864)
loaded kexts:
com.symantec.kext.SymAPComm 12.7.1f4
com.symantec.kext.fw    5.3.1f4
com.logmein.driver.LogMeInSoundDriver   1.0.3
com.symantec.kext.ips   3.10.2f23
com.symantec.kext.pf    5.7.1f4
com.symantec.kext.internetSecurity  5.4f4
com.apple.driver.AppleBluetoothMultitouch   85.3
com.apple.driver.AppleHWSensor  1.9.5d0
com.apple.filesystems.autofs    3.0
com.apple.iokit.IOBluetoothSerialManager    4.3.5f8
com.apple.driver.AGPM   110.19.6
com.apple.driver.ApplePlatformEnabler   2.2.0d4
com.apple.driver.X86PlatformShim    1.0.0
com.apple.driver.AppleMikeyHIDDriver    124
com.apple.driver.AppleOSXWatchdog   1
com.apple.driver.AppleMikeyDriver   272.18.1
com.apple.driver.AppleHDA   272.18.1
com.apple.driver.AppleUpstreamUserClient    3.6.1
Based on this log I see 2 problem makers.

One is the "Symantec" that you should remove.

The second one is the "logmein" that you should also remove.