Yes, the folder is definitely read/write. The folder just stops responding like it has a corrupted table of contents. After windows exporer crashes, it will continually crash until I delete that containing folder, then all is ok.
PSData files save fine, as do csv files. I am sorry, I misunderstood that .mat files could not be loaded into picoscope, that was my bad
Thanks for the help and suggestions, I will probably just use the csv files as they are mostly going to be smaller in size.