I wouldn't be a good idea to "force" left alignment, as some browsers treat such content slightly differently to that with no specified (default) alignment.
In addition to checking the HTML for CENTER tags or ALIGN="center" attributes, take a look at the CSS file if you've modified it in any way.
In addition to checking the HTML for CENTER tags or ALIGN="center" attributes, take a look at the CSS file if you've modified it in any way.