Rory,I presume you installed with Michael's float installer (5.09.0 or 5.09.1) on Sourceforge?Several times I've gotten NSIS installer errors after a download and had to re-download.Today I took a fresh Toshiba (Intel) laptop than had never had Csound or any other specific music application loaded, and did not have a rtpa.dll or any other "portaudio" file.