The problem was introduced to Windows 7 by a recent update (KB 3086255). In my case it affects at least Shogun, Medieval, Rome, Medieval II and maybe a bunch of other old games I have not tested yet.

For the moment, I am enabling and disabling secdrv.sys manually as suggested in the opening post of this thread:

http://forums.civfanatics.com/showthread.php?t=552308

That is a rather inconvenient workaround, so I consider uninstalling the guilty update.

I am wondering:

1) Would the update be automatically reinstalled, so I'd have to keep uninstalling it? (That would defeat the purpose of convenience.)

2) Is the secdrv risk small enough to make it defensible to accept it for the sake of convenience? Or is skipping any security update plainly stupid?