Hi.
I have a similiar issue with Symantec Endpoint Protection, which I had to update for 10.11.4 Beta.
Just to be sure its not an issue on my side, so I can wait for next beta version.
19/01/16 16:03:20.084 com.apple.kextd[47]: ERROR: invalid signature for com.symantec.kext.internetSecurity, will not load
19/01/16 16:03:20.448 com.apple.kextd[47]: ERROR: invalid signature for com.symantec.kext.ips, will not load
19/01/16 16:03:20.966 com.apple.kextd[47]: ERROR: invalid signature for com.symantec.kext.ips, will not load
19/01/16 16:03:24.045 com.apple.xpc.launchd[1]: (com.symantec.uiagent.application) This service is defined to be constantly running and is inherently inefficient.
19/01/16 16:03:41.063 SymDaemon[80]: Loading Signed version of Kext in 10.9 OS X: /Library/Application Support/Symantec/AntiVirus/Signed/SymAPComm.kext
19/01/16 16:03:42.749 com.apple.kextd[47]: ERROR: invalid signature for com.symantec.kext.SymAPComm, will not load
19/01/16 16:03:42.776 SymDaemon[80]: Loading Signed version of Kext in 10.9 OS X: /Library/Application Support/Symantec/AntiVirus/Signed/SymAPComm.kext
19/01/16 16:03:43.317 com.apple.kextd[47]: ERROR: invalid signature for com.symantec.kext.SymAPComm, will not load
19/01/16 16:03:44.333 com.apple.kextd[47]: ERROR: invalid signature for com.symantec.kext.ips, will not load
19/01/16 16:03:44.953 SymDaemon[80]: Loading Signed version of Kext in 10.9 OS X: /Library/Application Support/Symantec/AntiVirus/Signed/SymAPComm.kext
19/01/16 16:03:45.477 com.apple.kextd[47]: ERROR: invalid signature for com.symantec.kext.SymAPComm, will not load
19/01/16 16:03:45.493 SymDaemon[80]: Loading Signed version of Kext in 10.9 OS X: /Library/Application Support/Symantec/AntiVirus/Signed/SymAPComm.kext
19/01/16 16:03:45.869 com.apple.kextd[47]: ERROR: invalid signature for com.symantec.kext.SymAPComm, will not load