Archive Downloads are incomplete.

[Dreamrg]

I have a problem when users download an entire Album from my Kplaylist site.
The inbuilt zip correctly zips the file but when a user downloads the file it's cut short and therefore the downloaded .zip is corrupted.
When i do a download locally all is fine. I think this is a problem with a timeout or size var in IIS or PHP.
Does anyone have any ideas on how to fix this issue?

Thanks.