lan malfunction

Hello,
I can copy in my computer files from all computers of the network.
My Outlook and Internet work well.
I can copy from my computer to the network .zip files, but...

I can't copy from my computer to the network other files (xls, doc).

Two different messages:
1.- the network is missing
2.- you can't access to the file (this one that is in my computer and I try
to copy)

can you help me?

sorry my english