That one can occur if there is a non standard Windows "Tahoma" font installed or the "Tahoma" font is not installed at all or has become corrupted.
You can check it if you open the Vista Control Panel "Fonts" option (blue Windows logo button > Control Panel > Appearance and personalization > Install or remove a Font)
Look in the list of installed fonts that comes up for all fonts named "Tahoma" you should only have "Tahoma" and "Tahoma Bold" listed, remove any extraneous Tahoma entries, or reinstall the font if missing or if it has become corrupted.
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NOTE: The Customer Support forums are best for Player-to-Player help, for more direct and official support, please submit a ticket to the appropriate team via the form here.
After contacting support, log into your email webpage to add noreply@turbine.com and accountsupport@turbine.com to their "safe senders" list and your contacts list/address book. Be sure to check Spam/Junk Mail folders as well since most email providers do not let external email programs or cell phones download mail flagged this way.