Some users are experiencing issues with third-party browsers on 8.1 Preview
Windows 8.1 is still in testing stage, so it's more or less obvious that compatibility, performance, and stability issues could be experiencing while trying out the OS update.It now appears that some users are not allowed to launch Firefox and Chrome on their computers after installing Windows 8.1 Preview, so the built-in IE11 remains the only option when it comes to browsing the web.
“I updated to 8.1 yesterday and some strange things have happened since then. For one, now my PC requires a two step to turn it on. First I have to turn it on (nothing happens), then I have to hard shut down to turn it on again; for it to work. After that, Firefox and Chrome no longer work. The only browser currently working is IE and it does not do what I want to do so well,” one user wrote on Microsoft's support forums.
On the other hand, we can confirm that both Chrome and Firefox work just fine on our Windows 8.1 Preview machines, so it's most likely a glitch caused by specific hardware configurations.