Dear Chris & all,

Found the PC way to reset flash drive, Sadly PC at library did not give me administrator privileges. Couldn't seem to access the right pane in disk utility, but will take another look at it Thanks Chris. The realisation has been dawning on me for some time that I'm not going to work in a chemistry lab again. They won't let me drive, so working around hazardous substances just isn't going to happen. May as well try to work round computers.

John