In attachment compressed Logfile.csv from Process Monitor after manual start vsthost.exe.
Related thread: Updated foo_midi to v1.150; lost use of Hyper Canvas VST, EDIROL HQ SS (http://www.hydrogenaudio.org/forums/index.php?showtopic=92899&st=0&gopid=782616&#entry782616)
Another logfile from Process Monitor using another vsthost.exe.
Logfile1.rar - Foobar2000 running, File -> Preferences -> Playback -> Input -> MIDI synthesizer host
Logfile2.rar - vsthost.exe started manually (as before)