Question re: Sitemaps & SEO

Hi everyone - when I visit the sitemap.xml page that I expect to see after installing the Sitemaps & SEO plugin, I get a list of errors like this:

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Warning: mkdir() [function.mkdir]: SAFE MODE Restriction in effect. The script whose uid is 512 is not allowed to access / owned by uid 0 in /home/****/public_html/wp-content/mu-plugins/simple-sitemaps.php on line 87

Warning: mkdir() [function.mkdir]: SAFE MODE Restriction in effect. The script whose uid is 512 is not allowed to access //home owned by uid 0 in /home/****/public_html/wp-content/mu-plugins/simple-sitemaps.php on line 87

Warning: mkdir() [function.mkdir]: SAFE MODE Restriction in effect. The script whose uid is 512 is not allowed to access /home/****/public_html/wp-content/blogs.dir owned by uid 99 in /home/****/public_html/wp-content/mu-plugins/simple-sitemaps.php on line 87

Warning: mkdir() [function.mkdir]: Unable to access //home/****/public_html/wp-content/blogs.dir/1/files in /home/****/public_html/wp-content/mu-plugins/simple-sitemaps.php on line 87

Warning: file_put_contents() [function.file-put-contents]: Unable to access //home/****/public_html/wp-content/blogs.dir/1/files/sitemap.xml in /home/****/public_html/wp-content/mu-plugins/simple-sitemaps.php on line 89

Warning: file_put_contents(//home/****/public_html/wp-content/blogs.dir/1/files/sitemap.xml) [function.file-put-contents]: failed to open stream: No such file or directory in /home/****/public_html/wp-content/mu-plugins/simple-sitemaps.php on line 89

Warning: Cannot modify header information - headers already sent by (output started at /home/****/public_html/wp-content/mu-plugins/simple-sitemaps.php:87) in /home/****/public_html/wp-content/sitemap.php on line 29
http://REICtr.com/1/hello-world/ 2009-03-15T18:07:43+00:00 1.0
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Note - Safe Mode is definitely *OFF* on this account.

Any ideas? Thank you so much!