I've found an issue that I think affects the current version of VIVO. I noticed it on a server running an old version (v1.5, I think), but I looked at the source code for the most up-to-date release (here and here); to my understanding, the current code likely also has this issue.
I noticed that the GraphML file downloaded from the Co-Author Network view of a researcher does not html-encode ampersands, causing the XML to be invalid. I'm not sure whether this could affect other special characters beyond ampersands, as well. This has a simple workaround (opening the XML file in a text editor and replacing all "&"s with "&"), but took me a while to diagnose and fix today. This may be corrected in the current version of VIVO; in case not, though, I thought to report it.
Thank you for your work on this project!