There was an error opening this document. The file is damaged and could not

Hi

I have a user who has emailed me a PDF document from her ipad. When I open in my windows 7 PC I get an error which says:

There was an error opening this document. The file is damaged and could not be repaired.

On the attachment I can see two files attached.

One says :Finance.pdf(735KB)
second one says: ATT00001.htm(406KB)

Please suggest is there a way of opening this PDF document in a windows 7 PC.I remember there was a software which used to open and I lost track of it.

Any help much appreciated

Thanks