[MonoDevelop] Monodevelop crashes because it cant find Helvetica 10?

[nit etc]

When I try to run monodevelop:
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[shell]$ /usr/local/bin/monodevelop 
Creating DefaultWorkbench

** (MonoDevelop:25266): WARNING **: Cannot open font file for font Helvetica 10

** (MonoDevelop:25266): WARNING **: Cannot open fallback font, nothing to do
[shell]$
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Any ideas?

Thanks