Hello, I installed an upgrade from Poser 11 to Poser 13. It keeps crashing when I start it.

No 

initialization??

Picassofrau

Just my (possibly) uninformed opinion - but the Renderosity's authentication server may well be hosed up (again), possibly because of the new security measures Tim referenced in a different thread. Login problems emerged over the past weekend. Now tits blocking registered users who use a VPN - which pretty-much everyone on the internet these days should be using. Instead of trying to figure out whether our systems are errant, I suggest waiting until Renderosity resolves whatever it (insert your own descriptor here).   

Sorry, I mistyped 'tits'. Should have been "it is". 

I can log in to Poser just fine. The site is a different matter. I don't know if this will help anyone, but I was getting one of those 403 messages when I tried to log in with my PC (Chrome browser and Malwarebytes VPN).  But I noticed I could access the site OK with my ipad.

So, I uninstalled BOTH malwarebyes and Chrome, getting rid of all the stuff in the browser cache. After that I reinstalled BOTH Chrome and Malwarebytes, and now I can access the site without getting the 403 error message.

Problem STILL exists with the amount of time it takes to log in.  It hangs horribly. But at least there is no more 403 error.

There have been some site issues recently, which are being worked on. If you get a 403 error, please contact support https://support.renderosity.com/ and include your country, browser, and if you use a VPN

I haven't heard that it will affect Poser usage. You might want to contact Poser support for help with that. https://support.posersoftware.com/