C7 Elements won't install on Vista

After a friend of mine destroyed his C4 dongle and lost his license along with it I suggested it might be time to upgrade.

His needs are simple so I recommended he take a look at the C7 Elements trial version for evaluation. After downloading and unzipping however we’ve found that it won’t actually install on his Windows Vista desktop. I’m aware Vista is not officially supported but it does seem that ordinarily it will install and run OK. In this case however the installer simply vanishes from the screen and nothing happens. We’ve repeated the process including re-downloading etc. I’ve also done a clean boot with startup items disabled etc. I’ve updated Shockwave (I think the installer uses this??). I’ve searched high and low for a solution online and here but so far no luck. Just wondered if anyone here had any thoughts or ideas?