windows vista
service pack1

i have the program running in admin mode.

the PNGs seem to be showing ok with the correct colours but no opacity at just a solid colour (purple where its purple, white where its white etc. not the solid grey when the PNGs fix is incorrect), my machine has IE7 so i am testing for IE6 and IE8 but it occurs in IE7 in IETester too but not in the actual browser. ok the opacity is a lot darker in IE but its solid when i test in IETester.
is this a common issue? its not really a big issue for me just curious to know if the PNGs are showing correctly in IE6 browser just difficult to find a computer that actually has this browser despite the fact that browser usage stats still indicate a significant level of usage.