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It looks like a corrupt file or two. Reupload /kernel/config.php and try again. You are getting the Error [Xoops]: Class XoopsConfigHandler because your installation can not read the /kernel/config.php properly.
If you upload new files and still encounter the problem another possibility is that your initial download may have been corrupted during the download or during decompression. Download the package again (to a different folder), unpack and reupload just the /kernel/config.php to see if that solves the problem. If this fails, reupload all the files and start over.
If you have to reupload all the files, do not overwrite your mainfile.php, unless you don't care about starting from scratch. If you reupload all your files (not just one or two) you will have to reset the permissions on your /uploads, /cache, and /temp_c directories as the perms will be overwritten along with them.
Just a few useful tips, hope this helps.