We have been aware, but unable to reproduce, an issue some customers have where GMS2 crashes during the splash screen at the "Installing runtimes ..." stage. For a little while we have had this bug report marked as a known issue and have been discussing the issue directly with affected customers via support tickets.
We identified the issue as being that a third-party internet security tool by the company LavaSoft was blocking GMS2 from downloading files, which can be confirmed on your system by checking Windows' event viewer and seeing the crash information for GameMaker (or generating a DXDiag report and scrolling way down the log to the Diagnostics section).
In an DXDiag report you'll see the following:
Windows Error Reporting:
+++ WER0 +++:
Fault bucket 120714890654, type 4
Event Name: APPCRASH
Response: Not available
Cab Id: 0
Please note, many of our affected customers were not aware they had this software on their system, so this might apply in your case also.
We have also, since this FAQ was originally published, heard an example of GMS2 crashing when trying to show the Start Page and again this was due to LavaSoft blocking internet access. In this case, the LavaSoft product had been (unknowingly) installed after GMS2 had been installed and set up.
Looking at LavaSoft's own support pages confirms they are aware of this issue with older versions of their Web Companion software failing to uninstall properly and causing this type of instability with various software products over the last couple of years. Accordingly, our advice is to follow the steps at this LavaSoft support page to remove the files at fault if you no longer wish to use their products, or to apply their recent patch (Option #3) to bring your installed software up-to-date if you do want to use their software alongside GMS2.
Please be aware we have not tested their patch, so we make no guarantees this fixes their issue.
If you require more help removing their products, or further information on which products are affected, please see LavaSoft's Support Center.