You should install these:
For Project64 2-2.3.
VS2008 Redistributable.
https://www.microsoft.com/en-gb/down...s.aspx?id=5582
For Project64 2.4 or emucr versions:
VS2015 Redistributable.
https://www.microsoft.com/en-us/down....aspx?id=53587
Also make sure to install directx9.
https://www.microsoft.com/en-gb/down...s.aspx?id=8109
You might not have needed to install these before. As many times they get installed with games etc. But a new install of XP, you will need to install them.
Edit:
It's about time for Project64 to check if the Visual Studio runtimes are installed, and if not, download and install them on startup. Many apps and programs do this.