After renaming / moving the files, I get, after a longer wait period, the following (new) error: inaccessible boot device. I'll check my BIOS next to see what my disk settings are.
I also did 'Sfc /Scannow /OFFBOOTDIR=D:\ /OFFWINDIR=D:\Windows'. It found a few problems and corrected it. A second run did not find any problems (same for chkdsk).
..\system32\logfiles\srt\srttrail.txt is clean now, aswvmm.sys isn't mentioned any longer. I'll move and rename all asw*.* files and folders back to their original location, hopefully triggering the aswvmm.sys log entry again, and see if I can fix Windows another way. And I am still wondering... Can't the file simply be replaced?
Post-edit: putting all avast files back in its place did not repeat the original problem (which is the srt-log reference of aswvmm.sys)