Outlook 2010 pdf attachments arriving as html in message body

Sample from the message body:

</html>
--=_4a4365c17632c831e1c9b3b161ac1302
Content-Transfer-Encoding: base64
Content-Type: application/octet-stream;
name="capitalpacific702_03-29-2011_15:11:02.pdf";
Content-Disposition: attachment;
filename="capitalpacific702_03-29-2011_15:11:02.pdf";
JVBERi0xLjEgDSXi48/TDQoxIDAgb2JqDTw8IA0vVHlwZSAvQ2F0YWxvZyANL1BhZ2VzIDMgMCBS
IA0+Pg1lbmRvYmoNMiAwIG9iag08PCANL0NyZWF0aW9uRGF0ZSAoRDoyMDExMDMyOTE1MTIzOCkN
L01vZERhdGUgKEQ6MjAxMTAzMjkxNTEyMzgpDS9Qcm9kdWNlciAobGlidGlmZiAvIHRpZmYycGRm
IC0gMjAwNjAzMjMgLyBkKQ0vQ3JlYXRvciAoSW1hZ2UgQ29udmVyc2lvbiBMaWJyYXkgVjAuMCBi
eSBDb21tZSkNPj4gDWVuZG9iag0zIDAgb2JqDTw8IA0vVHlwZSAvUGFnZXMgDS9LaWRzIFsgNCAw

Hi sunstreamnetworks,

1. Can you verify whether this appears in the users OWA? Or does it appear as an attachment?

2. Have you created another profile in Outlook 2010 for the user in question?

3. Is Outlook and Exchange 2010 full patched and up to date?

Thanks for you help & suggestions, answers below.

1) It is the same in OWA, no attachment.
2) I have not tried to create a new profile
3) Both are fully patched & updated

My hunch is your AV, its always a third party product which causes Exchange or Outlook to behave this way.

Have you excluded your AV on the Exchange server to exclude certain directories? http://technet.microsoft.com/en-us/library/bb332342.aspx

Can you disable AV on the affected client machine as a test, and possibly disable the Outlook AV protection, if enabled: http://www.msoutlook.info/question/20

Please advise how you get on.

Hi Netflo,

Apologies for my delayed response.
Confirmed AV doesn't seem to be causing the issue, I completely disabled it on both sides with no luck. Is there anything else you can think of that may be causing this? The last step is to create a new profile, which I am hesitant to do until I feel i've exhausted all other options...
Thanks for your help!