I'd look into what's causing that. My guesses are: firewall, anti-virus, spyware (or anti-spyware), and hardware issues, in roughly that order. Network issues can be terrible to diagnose. You should NOT be getting corrupt TCP transfers though with anything even remotely approaching regularity (there's a checksum and guaranteed delivery for those packet types).
One way I've used in the past to find a problem on my network is to build a few large sets of files with known MD5 hashes (some big files, some medium, and then a bunch of really tiny ones). Then, transfer these files all at once from one computer on your local network to another (starting multiple copy operations across the network -- not just one big one -- to really stress the hardware). Of course, this requires that you have access to two machines. If you don't, then it'll be more difficult to test, but you could try downloading files from FTP sites where they do provide MD5 hashes (linux distros are good for that).
Either way, once you can recreate the issue with regularity, then start one by one eliminating possible culprits. EG: Test. Check for corruption. If found, uninstall anti-virus. Test. Check for corruption. If still found, reinstall Anti-Virus and try the next suspicious culprit. So on and so forth. With a little luck, you'll eventually find something that can reliably stop the corruption (make sure to test again a few times for good measure even when you think you found it).
On my own personal systems, I have found bad network cards (and they were high-quality Intel branded add on cards) causing the issue. I've also had MANY issues with systems with nForce motherboards and the nVidia Firewall installed (that TCP offloading "feature" they had in nForce 3-4 has known issues). I've never seen an Anti-Virus or software firewall app (other than nVidia's thing) do it myself, but I've heard about it happening enough to know it can be real.