|I accept that if you are going to reformat it doesn't matter much but I would like to check my understanding of the current FAT32 situation.|
The C drive (for some weird reason) has been given the partition name "windows". This has everything in it and is 399 GB total.
The normal Windows folder is presumably a sub-folder of this (usually about 10GB).
So the exact path to what is normally called the Windows folder is presumably:
C:\Windows (where C happens to have the confusing "partition name" of Windows).
The free space on the C drive is 95gig.
Is that lot right?
While posting this I see you have now been asked to post the results of chkdsk c: (which should clarify the situation).
We all live on a ball.