ligroce -- You have 241 code warnings, of which you've made the most common error, and that's where you didn't start your site off with the required <!DOCTYPE Declaration>.
A DOCTYPE Declaration is mandatory for most current markup languages and without one it is impossible to reliably validate a document. The DOCTYPE defines the version of the document like -- HTML 4.0.1, XHTML 1.0, 1.1, ...etc.
SiteBuilder is a bad template to use, as it has a hidden javascript file running in the background.
Now; here's a "partial list" of rest of your code warnings you may wish to fix (can't list all of them due to the limit of 10,000 characters):
line 3 column 1 - Warning: missing <!DOCTYPE> declaration
line 18 column 139 - Warning: '<' + '/' + letter not allowed here
line 18 column 166 - Warning: '<' + '/' + letter not allowed here
line 20 column 135 - Warning: '<' + '/' + letter not allowed here
line 3 column 1 - Warning: <script> isn't allowed in <html> elements
line 30 column 5 - Warning: <script> isn't allowed in <table> elements
line 77 column 7 - Warning: <script> isn't allowed in <tr> elements
line 139 column 7 - Warning: <script> isn't allowed in <tr> elements
line 242 column 7 - Warning: <script> isn't allowed in <tr> elements
line 265 column 93 - Warning: unescaped & or unknown entity "&b"
line 265 column 99 - Warning: unescaped & or unknown entity "&l"
line 265 column 103 - Warning: unescaped & or unknown entity "&f"
line 329 column 7 - Warning: <script> isn't allowed in <tr> elements
line 30 column 5 - Warning: <script> isn't allowed in <table> elements
line 398 column 84 - Warning: missing </span> before <table>
line 398 column 707 - Warning: missing </span> before </td>
line 398 column 663 - Warning: missing </font> before </td>
line 398 column 660 - Warning: missing </b> before </td>
line 398 column 179 - Warning: plain text isn't allowed in <tr> elements
line 398 column 796 - Warning: discarding unexpected </span>
line 398 column 803 - Warning: discarding unexpected </font>
line 398 column 810 - Warning: discarding unexpected </b>
line 398 column 1745 - Warning: missing </span> before </td>
line 398 column 1701 - Warning: missing </font> before </td>
line 398 column 1698 - Warning: missing </b> before </td>
line 398 column 1443 - Warning: plain text isn't allowed in <tr> elements
line 398 column 1835 - Warning: discarding unexpected </span>
line 398 column 1842 - Warning: discarding unexpected </font>
line 398 column 1849 - Warning: discarding unexpected </b>
line 398 column 3697 - Warning: missing </span> before </td>
line 398 column 3653 - Warning: missing </font> before </td>
line 398 column 3781 - Warning: discarding unexpected </span>
line 398 column 3788 - Warning: discarding unexpected </font>
line 398 column 3932 - Warning: discarding unexpected </span>
line 29 column 3 - Warning: content occurs after end of body
line 461 column 47 - Warning: unescaped & or unknown entity "&t"
line 461 column 60 - Warning: unescaped & or unknown entity "&f"
line 29 column 3 - Warning: content occurs after end of body
line 17 column 5 - Warning: <script> inserting "type" attribute
line 23 column 1 - Warning: <script> inserting "type" attribute
line 29 column 3 - Warning: <body> proprietary attribute "onresize"
line 29 column 3 - Warning: <body> proprietary attribute "marginheight"
line 29 column 3 - Warning: <body> proprietary attribute "marginwidth"
line 29 column 3 - Warning: <body> proprietary attribute "topmargin"
line 29 column 3 - Warning: <body> proprietary attribute "leftmargin"
line 29 column 3 - Warning: <body> proprietary attribute "hspace"
line 29 column 3 - Warning: <body> proprietary attribute "vspace"
line 76 column 7 - Warning: <script> inserting "type" attribute
line 30 column 5 - Warning: <table> proprietary attribute "height"
line 103 column 247 - Warning: <br> proprietary attribute "soft"
line 113 column 270 - Warning: <br> proprietary attribute "soft"
line 115 column 50 - Warning: <img> lacks "alt" attribute
line 123 column 62 - Warning: <img> lacks "alt" attribute
line 132 column 435 - Warning: <img> attribute "src" lacks value
line 132 column 2897 - Warning: <img> attribute "src" lacks value
line 132 column 2897 - Warning: <img> lacks "alt" attribute
line 132 column 3307 - Warning: <img> attribute "src" lacks value
line 132 column 3307 - Warning: <img> lacks "alt" attribute
line 160 column 205 - Warning: <br> proprietary attribute "soft"
line 172 column 176 - Warning: <br> proprietary attribute "soft"
line 184 column 157 - Warning: <br> proprietary attribute "soft"
line 191 column 50 - Warning: <img> lacks "alt" attribute
line 460 column 103 - Warning: <script> inserting "type" attribute
line 460 column 190 - Warning: <script> inserting "type" attribute
line 398 column 84 - Warning: trimming empty <span>
line 398 column 3697 - Warning: trimming empty <span>
line 398 column 3653 - Warning: trimming empty <font>