I've got the same sort of errors. My Clamscan errormessage is a bit longer.
LibClamAV Warning: Unknown machine type in PE header
LibClamAV Warning: Unknown subsystem in PE header
LibClamAV Warning: Unknown machine type in PE header
LibClamAV Warning: Unknown subsystem in PE header
LibClamAV Warning: Unknown machine type in PE header
LibClamAV Warning: Unknown subsystem in PE header
LibClamAV Warning: Unknown encoding type "quoted-printable/4.2.0-dev" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net
LibClamAV Warning: Unknown encoding type "8bit;" - report to bugs@clamav.net