That's a bad translation from French, most likely, since https://www.google.com/search?q=%22could+be+corrupted+could+not+open%22 only finds your post here, and nothing else.
Try searching the original untranslated message.
Moreover, there is no office 7. There's MS Office XP=2002, 2007, 2010, 2013, 2016, 365, but no 7.
It's usual for Office to open files received via mail or downloaded from Internet with a security warning. But when you say you want to open it anyway, that works fine and if you save it, it won't give that message again. That's quite something else than "could not open".
Try copying those files to a FAT32 formatted USB-stick and back again. Then it loses the metadata telling where it came from. Does that work?
Windows 7 pro 64bits, office 7 on several computers.
Since some months, when i received a mail ,whith a word file attached, and i want to open it, i received a msg " could be corrupted could not open".
This is the same for power point files.
I did not found a way to correct this problem.
Any body could help me ? Tks