Notes about the XSO 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 XSO file type is primarily associated with 'Expresso' by Ultrapico. A tool chest for building and testing regular EXPRESSiOns for Microsoft Windows .NET. The .XSO extension is used to store/recover all details of a given project.