Outlook 2010 is losing text in sent messages

MS Outlook 2010 started losing text is I send message with attachments. The person who received the message could see only attachment but the text field was empty. That started after I installed Windows 7 instead of Windows 8, but I am not sure if it's the problem. Also it takes a lot of time to send message with large attachment, 10-15 mins, I don't think it's normal as well.
