Zorin 15.1 download faliure

Hi All,
I've finally got things ready to upgrade from my trusty zorin 9 to the latest version but have encountered a problem with downloading the 15.1 lite iso.
I've been trying to get it from the Zorin website and a couple of other sourceforge mirrors as well but keep getting the same messages.
Sometimes the download just stops about halfway through: "failed"
Other times even before the download starts, when the dialogue box that asks where to save the file appears, I get: "/tmp/mozilla_justin0/002hFluD.iso.part could not be saved, because the source file could not be read." and "There is not enough room on the disk to save /tmp/mozilla_justin0/RqepZ+tH.iso.part." on top of each other! These wee boxes just can't seem to agree with each other....
I've tried running firefox in safe mode, and also tried through google rather than my more usual duck-duck-go, but to no avail.
The motherboard is an Asus P5K-VM running Zorin 9.
Any ideas what the problem could be?
Cheers
Justin

Hi All,
I've finally got things ready to upgrade from my trusty zorin 9 to the latest version but have encountered a problem with downloading the 15.1 lite iso.
I've been trying to get it from the Zorin website and a couple of other sourceforge mirrors as well but keep getting the same messages.
Sometimes the download just stops about halfway through: "failed"
Other times even before the download starts, when the dialogue box that asks where to save the file appears, I get: "/tmp/mozilla_justin0/002hFluD.iso.part could not be saved, because the source file could not be read." and "There is not enough room on the disk to save /tmp/mozilla_justin0/RqepZ+tH.iso.part." on top of each other! These wee boxes just can't seem to agree with each other....
I've tried running firefox in safe mode, and also tried through google rather than my more usual duck-duck-go, but to no avail.
The motherboard is an Asus P5K-VM running Zorin 9.
Any ideas what the problem could be?
Cheers
Justin

This really could be a disk issue, a net connection issue, a server issue...
I just tried a test download. Averaged about 4megs per second.
I didn't have any problems, but Zorin 15 is quite popular and I have experienced lag, delays or such before. So have others and on occassion, someone will pop up on the forum asking why the download is failing or only moving at 2kb/s
Sometimes, it is fixed by waiting a couple hours and trying again later.
This should be your first option simply because it is the easiest and has a good probability.

After that, should check your hardware/disk for any errors and your network. OR, you can do some checking while you wait a bit...

EDIT: I just downloaded Zorin OS 9 and made it bootable on a USB drive. Booted up (default) and connected and launched Firefox and tried to download Zorin 15.
It gave ma a "Firefox is out of date error." I think that default was 47, FF is now on 71... Either way, I couldn't update FF because it kept wanting to install 71.

Thank you Aravisian, as it happens I did run an overnight memtest as soon as I had posted the original question and to my horror the results are not good.
I will look into replacing the ram (maybe time for an upgrade on that as well) and try again.
And if that doesn't work I'll try a different browser as well if I can find something up to date that will install.
I'll update with my results as and when.
Cheers

Also best source to download from is here:

https://sourceforge.net/projects/zorin-os/files/15/