This has been happening a lot.
I downloaded something for University (some lectures a friend put in a .rar for me), and it was from SharingMatrix.com (like RapdiShare, HotFile, MegaUpload and so on...)
It's roughly 300MB, and I started downloading. surprisingly it finished in about 10-15Mins. I checked it to unpack and it appears it hasn't downloaded fully. I read up on the cache system on Firefox, and changed mine to 1000MB. This has been happening a lot, and I must admit I do download a fair bit of big files (over 200MB). I had downloaded something today before, could this be why? is it my computer, or FireFox?
The security programs I have are:
Malwarebyte's Anti-Malware (Paid)
ESET NOD32 anti virus (Paid)
Any help? :)