Installation stuck at "Prefetching information"

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I've set all of the files to 777 after repeatedly trying get C5 to install...

It still fails when all files and folders have 777 read,write,execute permissions

Can anyone tell me what the prefetching information stage is actually doing? So that I might be able to find out what is going wrong? I have the same issue on two other servers on my network...

Thanks in advance