SEEM TO HAVE FOUND THE SOLUTION! Read: @ Pill Monster: I was searching Google for this problem and found this thread. I don't care you think it's too old, the fact is it is till relevant to my issue. And no, it's not my RAM. My RAM pass 100% with MEMTest86 for 24H. Beside, it would have produce error in Prime95 or Intel Burn test... After writing this post, I've pushed my investigation further. Some other mention a possible correlation between the issue and Samba share or some other OS network related incompatibility. There was also some mention of Firefox integrated anti-virus scanning. I first disabled Firefox anti virus scanning by typing "about:config" in the Firefox address bar, then search for: "browser.download.manager.scanWhenDone" And "services.sync.prefs.sync.browser.download.manager.scanWhenDone" I set them both to "false" I went back to Firefox option to take another look around, just in case. In the advanced section, under the Network tab, there is a connection setting to tell Firefox "how to connect to he Internet". I changed the setting from no proxy to auto-detect proxy, closed Waterfox, restarted it and went to Filehippo to get some download action going. To my complement amazement, I clicked on the download of Firefox 16.0 beta 2 link, pressed "save file" and left the following file requester open for over 2 minutes before I finally pressed "save" and then, miracle, the file was not corrupted. Tried with 2 other file, and still OK. I hope this is not a fluke and that my issue is FINALLY resolved for good! I,ll need further testing to find if it was the proxy of the anti-virus scanning.