Notes about the S7 file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The S7 file type is primarily associated with 'Sibelius' by Sibelius Software Ltd. Music notation file copied to PC from one of the Acorn platform Sibelius programs, e.g. Sibelius 7.