Errors on the server side when exporting Main Page as PDF or RTF

Steps to reproduce :

1.Login in as admin
2.Exporting the MainPage as PDF or RTF will work, but you will see some errors in terminal/console
Errors are multiple and are similar with these

2010-07-02 16:23:16,118 http://localhost:8080/xwiki/bin/export/Main/WebHome?format=pdf&language=en ERROR apps.FOUserAgent - Image not found. URI: . (See position 295:287)
2010-07-02 16:23:16,121 http://localhost:8080/xwiki/bin/export/Main/WebHome?format=pdf&language=en ERROR apps.FOUserAgent - Image not found. URI: . (See position 307:287)
2010-07-02 16:23:16,175 http://localhost:8080/xwiki/bin/export/Main/WebHome?format=pdf&language=en WARN apps.FOUserAgent - The following feature isn't implemented by Apache FOP, yet: table-layout="auto" (on fo:table) (See position 347:122)