stops repsonding while recording

When I stop a recording, often it says “not responding” and I have just lost a 45 mintue presentation.

Which version of Audacity? (look in Help > About Audacity)
Which version of Windows?

Further to Steve’s questions: what hard drive environment do you have?

I use four Seagate “Portable hard-drives” - external USB connect. They are designed to work with laptops and have in-built power-saving features - they “go to sleep” when not accessed, in order to save power. I use them connected to my desktop system. If I do not keep the primary drive permanently active (by playing music files through Media Player), it goes to sleep and can take a minute or more to “wake up” again when I try and write to it. The other three drives also go to sleep but seem to wake up much faster. I suspect that Windows is doing something just after “wake up” and before releasing the drive to my use - but I don’t know what.