hi mike,
is sharepoint 2010 your referred to sharepoint online 2010 or sharepoint server 2010?
if it is sharepoint online 2010, i'd like to confirm the following information:
1.does the error message only occur to the specific pdf file or all the pdf files?
2.will this issue happen to microsoft documents, such as word/excel/.. on his side?
3.can others attach this specific pdf file?
4.capture a screenshot of the message for analysis.
note: to insert a screenshot, click use rich formatting on this thread and click the insert/edit button.
we will keep assisting you based on your updates if you are using sharepoint online.
if it is sharepoint server 2010, as this forum mainly focuses on office 365 for business online services, i would suggest you post to our dedicated sharepoint server forum for help, which is dedicated in handing sharepoint server related issues.
thanks for your understanding.
sky