File corruption during HTTP Upload

I am running PHP 4.1.1 with Apache 1.3.20 on Windows NT, and have recently started observing a bizarre file corruption effect. I first noticed this when transferring an RTF file with an embedded image. On arriving at the web server, the image disappeared and, after examining the file I found 4 very small differences - the file size was not altered at all. Now I have found that zip files are becoming corrupted in transit. A perfectly good zip file appears on the webserver with various CRC errors! I'm using a simple http form to upload the files, and the problem only seems to occurr if the files are fairly large (typically 2Mb or more). However, I need to be able to transfer much larger files than these (intranet only). Please can anyone suggest where this apparent corruption could be coming from. Thanks, Julian Stevens -- ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ********************************************************************