I get that sometimes when the handoff isnt fast enough between 3g-4g and sometimes when i walk too far from wifi and it doesnt switch to 4g fast enough bc there are other wifi networks around that it wants to connect to.
I get this as well, on 3G, 4G, and WiFi. Chrome and default browsers. Most often with image files of various formats. Experienced with stock radios as well as with 4.0.4 radios.
Like 2defmouze said, but also clear the data for the "downloads" app. I had the same issues, and had cleared data from download manager, but it didn't fix it until I cleared it from downloads also. Not sure why.
That was on m2. I'm on r133 nightly now with no problems.