Slight problem with downloads

[#1]

Hi guys
I've got a problem with some files on offer for download.
My website is using a script which writes the file out to the socket in php for throttling and tracking etc.
On my former site (cpanel) it worked fine and the md5 hashes matched once the download had finished. Recently I've moved onto a plesk powered host. Now the downloaded files have different hashes each time I download them. I've re-uploaded the originals, run the script on the server to check the MD5 hash matches from the local originals and they're fine. It only changes on download.
Any ideas?

[#2]

No worries I've solved. it.
My mates VPS where the site is hosted has safe mode turned on for php - using set_time_limit(0) is generating php error output at the beginning of the file stream and thus corrupting the thing.