We're on Creo 2 M050, WC 10.1 M030. Our users have experienced not responding on startup after a crash too.
In many cases for us, we found the text/config.pro and text/config.sup was being merged down into the user's startup config.pro.
This caused our JLink apps to be loaded twice and causing a conflict. Sometimes it would throw a toolkit error, other times it wouldn't.
Fixing the startup config.pro solved that problem. We have an open ticket with PTC on it, but they gave us this article as a reason
(https://www.ptc.com/appserver/cs/view/solution.jsp?n=CS104667).
We've also experienced it in a few other cases but we haven't come to a solid answer. PTC's answer was "Just use Mozilla", until we had issues with Mozilla too. Things that have helped: Fewer models in workspaces, Fixing compatibility mode for IE, Enabling native XMLHTTP support for IE. They also gave us a set of config settings that might help (we already had most implemented) dm_network_request_size=100000, dm_http_compression_level=0, windows_browser_type=mozilla_based_browser, dm_network_threads=4, dm_synchronize_in_background=yes.
Something else I found that didn't apply to us but might help "Set the proxy settings similar to the Firefox (Mozilla browser) settings".