I've got a super secure javascript downloader* that I wrote, and it usually works alright. But I noticed, while trying to download a 90 meg file with it on a client's machine that on IE7, it's getting hung up about 1/3rd of the way through.  I've never tried to send a file that large through the iFrame and it works fine in other browsers.  Is there a size restriction on files that IE7 can read in an iFrame? * It's really just a PHP line that sets header(location: http://someplace/downloadbigthing.exe); after it does some logging and verification.  
Maximum file size for iFrame in IE7
php;iframe;download;headers;internet explorer 7