My understanding from your message is that it worked fine until a few days ago and then quit working. That sounds like a software compatibility issue from an update or a program that you installed. However, it could also be a corrupted file.
First - you didn't install and run "Connectivity Fixer Pro 1.2" from November 10th did you? If so, that may well be the source of your problem.
Check the integrity of your hard drive since it's pointless to troubleshoot if your hardware is failing. If you don't have a drive health utility then try the free PassMark DiskCheckup and confirm that "Relocated Sector Count" is still 0.
I'd also run System File Checker (enter "sfc /scannow" in a run box) to rule out corrupted files as an issue.
Once you know your drive is OK, and it most likely is, start Resource Monitor, click the "Network" tab and determine if you've got a bunch of stuff using all of your bandwidth in the background (all those auto-updates, for example). If you do, either wait for them to finish or kill them. You can't download if you don't have available bandwidth.
Try a different browser. My initial impression from your note was "it's a browser issue". You could be having a problem with one of your extensions / add-ons or you might have an unhelpful BHO (browser helper object) that you need to remove. And, I hate to say it, but it may be time to upgrade. There's nothing wrong with Vista but you need to take extra care (and make a backup) when upgrading to the latest versions of software because they're not always fully compatible.
Use a download manager. If you're using one now, use a different one.
If none of that works, when (and what) was your last successful GOTD download and can you download from other sites?