In SharePoint, if one of your fields is designated as a Rich Text or Enhanced Rich Text field, and your output is showing the HTML tags, then it very well could be an XSLT problem. When I found this, it was a DataView web part XSLT problem.

Look in the XSLT and see if you have something like the following in the code which shows the Rich Text field:

<xsl:value-of select="@YourFieldName" />

If so, change it so that your resulting XSLT tag shows it like this:

<xsl:value-of select="@YourFieldName" disable-output-escaping="yes" />

That should do it!