Clients can not open attachments

Windows 7 Ultimate

Build ID: 70feb7d99726f064edab4605a8ab840c50ec57a

which attachments? In a word processing file attached files?
Which software do the other clients use?

You should update to 4.3.3, you’re using rather ancient LO. LO has received tons of updates since Direct link to the download:

if your question is about others not being able to open LibreOffice files you send them, please see: Why can't my friends not open my attached libre documents?