Hello Michal,

Same problem with 5.19b4 and nothing special in the logs.

Now I know how to reproduce the problem instantly, I just have to put my computer in StanBy mode and Awake it.

Using Process Explorer from Sysinternals I see that stunnel produce a permanent "Other I/O" flow when problem appear.

I/O Other : "The rate at which the process is issuing bytes to I/O operations that do not involve data such as control operations. This counter counts all I/O activity generated by the process to include file, network and device I/Os."

OtherI/O is confirmed by Process Monitor that trace no File nor Registry nor Network activity.

But as stunnel still respond correctly to a Quit menu or any other menus and SSL requests I assumed that it may be some Thread going crazy so I compared running thread between normal stunnel behavior with the 25% CPU behavior and found that in fact there is a thread that do no terminate correctly.

Here is the Thread's stack :

MSVCR90.dll!_endThread+0x7d ntoskrnl.exe!memset+0x61a ntoskrnl.exe!KeWaitForMultipleObjects+0xd52 ntoskrnl.exe!KeWaitForSingleObject+0x19f ntoskrnl.exe!PoStartNextPowerIrp+0xba4 ntoskrnl.exe!PoStartNextPowerIrp+0x1821 ntoskrnl.exe!PoStartNextPowerIrp+0x1a97 ntoskrnl.exe!KeReleaseInStackQueuedSpinLock+0x5a afd.sys+0x61c1c afd.sys+0x51d3b ntoskrnl.exe!NtMapViewOfSection+0x15b7 ntoskrnl.exe!NtDeviceIoControlFile+0x56 ntoskrnl.exe!KeSynchronizeExecution+0x3a23 wow64cpu.dll!TurboDispatchJumpAddressEnd+0x6c0 wow64cpu.dll!TurboDispatchJumpAddressEnd+0x1fb wow64.dll!Wow64SystemServiceEx+0x1ce wow64.dll!Wow64LdrpInitialize+0x42a ntdll.dll!RtlIsDosDeviceName_U+0x1f5c4 ntdll.dll!LdrInitializeThunk+0xe ntdll.dll!NtDeviceIoControlFile+0x15 WS2_32.dll!select+0x9f stunnel.exe!OPENSSL_Applink+0xd3ec stunnel.exe!OPENSSL_Applink+0x961

Hope it help...

regards.

MT> Please try stunnel 5.19b4: MT> https://www.stunnel.org/downloads.html