A couple of days ago Windows updated to a new version. The update went without a hitch, and the system booted as usual. At some point a notification was shown about an unnamed "driver update", which too was successful. However, since then the system refuses to boot, showing a BSOD with an Page fault in nonpaged area error at aswstm.sys (Avast's "stream filter" driver).
I'm able to access recovery mode, and Kyhi's recovery tools and a live Linux distro are available as well. chkdsk /r found no errors. sfc /scanfile="aswstm.sys" raises an error: Windows Resource Protection could not perform the requested operation, with a log file stating Servicing stack shim unable to mark handle [some id]. I've not seen a memory dump at either C:\Windows or C:\Windows\Minidump.
Advice?