Tahoma as I recall is not part of the generic web font list. These are the standard font families:

font-family:Arial, Helvetica, sans-serif;
font-family:"Times New Roman", Times, serif;
font-family:"Courier New", Courier, monospace;
font-family:Georgia, "Times New Roman", Times, serif;
font-family:Verdana, Arial, Helvetica, sans-serif;
font-family:Geneva, Arial, Helvetica, sans-serif;

It would default to Times if it can't find tahoma.

Try that first then lets see where we are.