What kind or errors? Markup validation, for example, validates your HTML against Web standard. However, even if your HTML is not up to standard, browser may still render it correctly since browsers are forgiving as they must be able to handle all kinds or Web pages, including those authored 15 years ago. Therefore validation error will not necessarily make page render incorrectly in, say, IE, but it may make page render incorrectly in Safari on Mac and page won't pass validation of the W3C validator.
Thanks
------------------------------------------------------------
This posting is provided "AS IS" with no warranties, and confers no rights.