hi,

Welcome to the Forum

No promises, but here are a few longshot questions which may guide you...
Are there any macros in the files?
(perhaps the file creator doesn't want info to be "copied" or saved as. Or there is an infinite loop tied into a BeforeSave event macro.)
How big are the files?
Do they have a lot of complex formulae (esp CSE array formulae, sumproducts,indirect etc)?
Have you changed a network printer recently?

hth
Rob