LoadVars && IE && Windows problem

Okay so, I have a lump of mason and perl that spits out a html page with a flash movie which draws a nice little graph, given all the right params:

<OBJECT classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"
codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,0,0"
WIDTH="1000" HEIGHT="1000" id="bar" ALIGN="">
<PARAM NAME=movie VALUE="/flash/barchart.swf">
<PARAM NAME="FlashVars" VALUE="End=1&YaxisLabel=frequency&XaxisLabel=time&ChartLabels=MSGPING+TEST+ACCOUNT%2CMetalabs%2Enet%2CDEFAULT%2CBlackSpider%2CAnother+bleeding+test+ac count%2E%2E%2C&ChartValues=200%2C35%2C0%2C1011%2C4%2C&ChartTitle=Testing+one+two+three">
<PARAM NAME=loop VALUE=false>
<PARAM NAME=menu VALUE=true>
<PARAM NAME=quality VALUE=high>
<PARAM NAME=bgcolor VALUE=#FFFFFF>
<EMBED src="/flash/barchart.swf" FlashVars="End=1&YaxisLabel=frequency&XaxisLabel=time&ChartLabels=MSGPING+TEST+ACCOUNT%2CMetalabs%2Enet%2CDEFAULT%2CBlackSpider%2CAnother+bleeding+test+ac count%2E%2E%2C&ChartValues=200%2C35%2C0%2C1011%2C4%2C&ChartTitle=Testing+one+two+three" loop=false menu=true quality=high bgcolor=#FFFFFF WIDTH="1000" HEIGHT="1000" NAME="bar" ALIGN=""
TYPE="application/x-shockwave-flash" PLUGINSPAGE="http://www.macromedia.com/go/getflashplayer"></EMBED>
</OBJECT>

It works on:
Mac (os x)
IE
NetScrape
Safari
Windows
NetScrape

But NOT IE for windows; I have checked all the common things, plug-in version etc - but the flash app just doesn't 'see' the FlashVars param.
Can anyone see why??

Thanks
Robin...