File is read only.  

Use Save As and change name or save to another disk

File is locked.

Try opening as read only

Selected printer does not exist or is not connected

Disk is locked by software.

Unlock disk or try opening as read only

Connection to the file server has been broken

Disk's directory is bad

A file with that name already
exists

File is already open. 
 
Try opening as read only

File is locked by hardware

Disk is locked.  

Unlock disk or try opening as read only

File not found

Not enough system memory

Too many files opened

Disk not found

Disk is full.

Save on another disk or delete unneeded files

Too many files on disk.

Save on another disk or delete unneeded files

Not enough memory.

Close extra animations or palettes

I/O error

Mac error

Unknown Mac error %ld