It sounds like the file /App_Browsers/CSSFriendlyAdapters.browser file has been corrupted somehow. I would upload it again from the package and/or inspect it with a text editor. Its an xml file but it sounds like it has invalid xml. I have seen cases in the past where xml files sometimes get corrupted during ftp upload. I use FileZilla to upload files and it works well.
Hope it helps,
Joe