For the record - I use current Sigil on Win7, Win10, and Sigil 0.7.? on an oldish (pre Cinnamon) Mint.
Under the Show button below are the
discretionary programs I am running right now (win 7), not system drivers, codecs etc. That, I don't get the problem doesn't eliminate these as potential culprits as my usage of Sigil is trivial; doubt I use more than 10% of functionality. So it could be any one of the gadgets I use.
If the problem is due to a 3rd party program its likely to be something that appears in the tray - probably behind the little arrow - maybe even hidden. In the list below the bold items are those that appear in the notify/tray areas, and most of them are in startup.
One other

- have plug-ins been eliminated as the potential cause.
BR