i had the same problem https://forum.pfsense.org/index.php?topic=85869.0
here is the Solution
http://makandracards.com/makandra/1258-install-the-verdana-and-tahoma-fonts-under-ubuntu-linux
Arial, Verdana, Tahoma, and similar “basic” Microsoft fonts are not included in a vanilla Ubuntu installation. You should have these fonts because many designers consider them to be universally available:
Arial, Verdana, etc:
sudo apt-get install ttf-mscorefonts-installer
Tahoma:
wget http://download.microsoft.com/download/ie6sp1/finrel/6_sp1/W98NT42KMeXP/EN-US/IELPKTH.CAB
cabextract -F 'tahoma*ttf' IELPKTH.CAB
mv -f tahoma*ttf /usr/share/fonts/truetype/msttcorefonts/
chmod 644 /usr/share/fonts/truetype/msttcorefonts/tahoma*
fc-cache -v
rm -f IELPKTH.CAB