FreeFileSync supports copying locked or shared files by creating a Volume Shadow Copy of the source drive. This feature can be configured via Menu → Advanced → Global settings: Copy locked files.
Note The
volume snapshot created by the Volume Shadow Copy Service is used
when copying locked files only.
Accessing the Volume Shadow Copy
Service requires FreeFileSync to be started with administrator
rights.
Troubleshooting
If you experience problems using the Volume Shadow Copy Service a renewal of registration might help. Create and execute a *.cmd batch file with the follow content or enter directly via command line:
cd /d %windir%\system32
Net
stop vss
Net stop swprv
regsvr32 ole32.dll
regsvr32
oleaut32.dll
regsvr32 vss_ps.dll
Vssvc /register
regsvr32
/i swprv.dll
regsvr32 /i eventcls.dll
regsvr32 es.dll
regsvr32
stdprov.dll
regsvr32 vssui.dll
regsvr32 msxml.dll
regsvr32
msxml3.dll
regsvr32 msxml4.dll
Reference: http://support.microsoft.com/kb/940032