Probably what's happening is the server on which the whiteboard conversion process is running on does not have that font and is using the next closest approximation. Try changing the font used in the PPT to Ariel, adjust the spacing and then reload. It should then look fine. Another approach is to use the Sametime Print Capture. The Print Capture will convert the presentation on the client machine where the font is available. Then upload the resultant FST file and it should look fine.