I think we're getting somewhere.
Can you go into your registry using regedit (accessible from Windows start menu) and see if you can do a search in it for the following:
AB8902B4-09CA-4BB6-B78D-A8F59079A8D5
also look for this:
bf3a50c5-a9c9-4988-a005-2df0b7c80f80
Provide me any info you may garner on these two, such as process/driver names and whatnot. If you wanna just take a snapshot of what you find by all means.
I believe I've finally found some pattern. Evidently, there's some hold-up for the SMB redirectory, the UNC provider, and the filter manager (as well as NTFS). The former two items are related to networked files (like Windows file sharing) and the like, and the latter is an over-encompassing item involving any file I/O, hence its relation to NTFS. NTFS driver is also hanging up frequently. I'm also noticing this is happening only when your system is doing disk flushes
There may be a filter driver, like either from your antivirus, or from some software related to files sharing or network connections, that's holding things up. That, or your drive itself is experiencing issues.
Another thing, I found that IMEI (Intel Management Engine Interface) has a tendency to rear its ugly head immediately at download start and again when the download dies. I'm not sure if it has a relation to this, but I recommend getting rid of it anyways, it's a security risk.
Again, I think I'm on to something, but I'll peruse the data further. I would definitely like to figure out more on what's going on, such as your driver stack, so if it's at all possible when firefox download hangs, whip out
Process Explorer, right click firefox, and create a full dump to give to us. If you wish, you may even go so far as to provide us a kernel dump. As in, first set up to do manually forced crash by following instructions
here. Then after the restart, get firefox going, run another download, and as soon as it hangs manually force a crash (
first make sure your crashdumps are set to kernel dumps as explained
here). Send us the
MEMORY.DMP file located in Windows folder after that.
The kernel dump and the firefox dump provide two separate details: the former provides me what was going on in the background such as I/O and stuff and gives me details on driver stacks n all that jazz, whereas the firefox dump will provide me a direct look at what was going on with firefox at the time the download hung. Preferably you provide both, but if you wanted to choose one, I'd go for the kernel dump first.