Same issue as OP with me also on 2280. Disabled shields randomly. Have to re-enable.
Here are Windows log reports if useful:
20th August 10:15
Faulting application name: AvastSvc.exe, version: 12.3.3154.0, time stamp: 0x57b5c39d
Faulting module name: ntdll.dll, version: 10.0.10586.306, time stamp: 0x571afb7f
Exception code: 0xc0000374
Fault offset: 0x000dc7c9
Faulting process ID: 0x63c
Faulting application start time: 0x01d1fa5e98e29d67
Faulting application path: C:\Program Files\AVAST Software\Avast\AvastSvc.exe
Faulting module path: C:\WINDOWS\SYSTEM32\ntdll.dll
Report ID: 9351a8ae-c855-4d23-a919-3b358a2fbf33
20th August 11 36
Faulting application name: AvastSvc.exe, version: 12.3.3154.0, time stamp: 0x57b5c39d
Faulting module name: ntdll.dll, version: 10.0.10586.306, time stamp: 0x571afb7f
Exception code: 0xc0000374
Fault offset: 0x000dc7c9
Faulting process ID: 0x1974
Faulting application start time: 0x01d1fac640c96097
Faulting application path: C:\Program Files\AVAST Software\Avast\AvastSvc.exe
Faulting module path: C:\WINDOWS\SYSTEM32\ntdll.dll
Report ID: 701d68a9-5d6c-4ccb-8e7b-c9edf058c69a
19th August
Faulting application name: AvastSvc.exe, version: 12.3.3154.0, time stamp: 0x57b5c39d
Faulting module name: ntdll.dll, version: 10.0.10586.306, time stamp: 0x571afb7f
Exception code: 0xc0000374
Fault offset: 0x000dc7c9
Faulting process ID: 0xa94
Faulting application start time: 0x01d1fa2624ba7fb3
Faulting application path: C:\Program Files\AVAST Software\Avast\AvastSvc.exe
Faulting module path: C:\WINDOWS\SYSTEM32\ntdll.dll
Report ID: 45a7a5b4-560a-4efa-82d3-5aaaa8cf25b3
18th August
Faulting application name: AvastSvc.exe, version: 12.3.3149.0, time stamp: 0x57b193ba
Faulting module name: ntdll.dll, version: 10.0.10586.306, time stamp: 0x571afb7f
Exception code: 0xc0000374
Fault offset: 0x000dc7c9
Faulting process ID: 0x1b30
Faulting application start time: 0x01d1f8a80c1f2e63
Faulting application path: C:\Program Files\AVAST Software\Avast\AvastSvc.exe
Faulting module path: C:\WINDOWS\SYSTEM32\ntdll.dll
Report ID: 7b82399c-28b1-477b-b2ac-5acb9efaee64