Is there a Firefox extension that will...

Prevent corrupted downloads? When downloading big files over wi-fi, I'm finding that in many cases the file does not match the CRC/MD5/SHA signature, even though the download was fully completed.

 

I'm afraid not, as that sounds more like a problem of wireless reliability. You could try boosting the signal reception by disabling power saving features to the wireless chip. This can be done via the Power Manager as well as Device Manager (for fine-tuning settings).

 

That's odd, although I've seen it before. I have a friend that has all sorts of issues like this with an Atheros card in Linux. I've never had issues with downloading large files over WiFi, even stopping/resuming, multi-tasking and all sorts of stuff. Psyduck has a good suggestion. You might try updating your WNIC drivers and router/modem firmware as well.

 

It probably is a wireless reliability problem, but it'd be nice if there was an extension that could detect corrupt packets and trigger retransmission or something, like TCP is supposed to. Heck, even an extension that essentially downloads 2 copies of the file, does a bitwise comparison, and somehow resolves the differences in the two copies would be an improvement over the current solution of downloading full copies the exact same file 5+ times and hoping that one of them comes through fully intact, wasting many GBs of bandwidth and many hours of my time in the process.

@boinkyktwo: I tried flashgot and downloadthemall. Neither of them showed a statistically significant difference in the rate of corrupt files. Never heard of jdownloader though.

 

Jdownloader is only used to download files from hosting sites (megaupload, rapidshare, etc..)

 

True, even thus 99% of the people use it only for hosting sites.