Help! Certain HTML emails are received as plain text

OS: Windows 7
Software: Outlook 2007

The problem faced is that certain emails are received as plain text messages even though the sender originally sent in HTML format. My outlook is set to send and receive in HTML. I do not use AVG software. I called MS tech to no avail. I tried uninstalling and reinstallying outlook and even made a new profile to see if it will correct the problem. None worked.

Another person in the office with the same OS and outlook program is able to receive the same email as HTML. Please help!