It's ok for me to use 4images in XOOPS 2.0.5. After upgrading XOOPS to 2.0.5.1, the user account of 4images and XOOPS can't be combined anymore. There is also some message below:

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DB Error: Bad SQL Query: SELECT * FROM xoops_groups_users_link WHERE uid= AND groupid='1'
You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND groupid='1'' at line 1
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How can I fix the problem? Please help, thanks!!!!

hmmm.. the uid is missing from the SQL sentence... not sent with the page request, perhaps?