is your scratch disk on a separate volume.\
when photoshop works on large files, it uses a LOT of temp disk space. with a 70 meg file, that could run into the gig range and more.
check on your free disk space. do a clean up and see where that leaves you. i hate working with psd files. ever try to add 3d effects to a psd. you might as well go get a few beers, several hundred miles away...
i did a quick search on google for error 36 and in unrelated situations, the consensus says i/o error. without knowing more about your system, i wouldnt be able to say if thats an issue you could be experiencing.