Attached is a patch to fix some problems Emacs has with failing to report I/O 
and access errors. It affects MS-Windows which I don't use, so I'm filing it as 
a bug report to give people a chance to review it. The main idea is to signal an 
error for I/O errors that are not tame errors. Typically ENOENT and ENOTDIR are 
tame, whereas the rest are more serious.