I've set wmode="opaque" in the AC code as below:
----------------------------------------------------
<script type="text/javascript">
AC_FL_RunContent( 'codebase','
http://download.macromedia.com/pub/
shockwave/cabs/flash/
swflash.cab#version=9,0,28,0','width','750','height','242','src','Images
etc./welcomebanner','quality','high','pluginspage','http://
www.adobe.com/shockwave/download/download.cgi?P1_Prod_Version=ShockwaveFlash','movie','Images
etc./welcomebanner','wmode="opaque"' ); //end AC code
</script>
<noscript>
<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"
codebase="
http://download.macromedia.com/pub/shockwave/cabs/flash/
swflash.cab#version=9,0,28,0" width="750" height="242">
<param name="movie" value="../Images etc./
welcomebanner.swf" />
<param name="quality" value="high" />
<param name="wmode" value="opaque" />
<embed src="../Images etc./welcomebanner.swf" width="750"
height="242" quality="high" pluginspage="
http://www.adobe.com/
shockwave/download/download.cgi?P1_Prod_Version=ShockwaveFlash"
type="application/x-shockwave-flash" wmode="opaque"></embed>
</object>
</noscript>
----------------------------------------------------
It's now working in Safari but not in IE8, unsure about FF.