I too have a recently upgraded Sony laptop, upgraded from Win7-->W10. I have none of the problems with Edge you mentioned. I just tried it and not only do I not have a blank page, I was able to change it to a predefined page; MSN.com, but also with a custom page. I also was able to download a PDF manual for my desktop from the Dell support download page, and it worked perfectly. I suspect you have a bigger problem with your W10 upgrade.
You might take a look at this post, as it covers some typical erratic behavior including error codes on W10 systems that were recently upgraded: http://www.bleepingcomputer.com/forums/t/596189/cant-install-windows-10-error-code-80004005/
The fact that you aren't receiving an error code doesn't bely the fact that you are getting abnormal behavior with the Edge browser, that I don't get on my system which appears to be working perfectly.
The main thing we see here with upgraded systems are that when they are not running perfectly, and have no virus/malware infections, or any kind of hardware failures, we see smooth upgrades. Since you've tried some of the suggestions here without success, I might suggest you have a failing piece of hardware or general Windows system file corruption. Before you go off and try more software solutions, you should consider testing your hardware first, as no software on the planet can fix broken hardware.
Here's a link to help you with both: http://windowsforum.com/threads/cursor-cannot-reach-top-of-quick-launch-area.214710/#post-654289
As Windows8.1 systems are getting to be 3 yrs. old or so, it's not unlikely that you could have a failed or failing hard drive. Hard drives in desktops begin failing after 3 yrs. old, and laptops, 1-2 yrs. depending on how many times they are dropped or used as frisbees-take your pick.
And like you said, you have other browsers to do your daily tasks, but if you are really annoyed you can follow some of the above tips and try to correct the problem (it is correctable) if you're willing to do the necessary troubleshooting and possible reinstallation or failed hardware replacement required. Alternatively, you can consider contributing to the economy by taking your desktop into your local repair shop and paying them to fix this problem for you!!
Best of luck and let us know how it works out,
Edited by BIGBEARJEDI, 12 November 2015 - 08:50 PM.