26.0.0.131 still locking up win10 firefox 54

Thank you for reporting the issue; however, there's not sufficient detail to investigate effectively.

Please see the following guide on how to report a crash or error:

https://helpx.adobe.com/flash-player/kb/report-flash-player-crash.html

Also, if you're not using 64-bit Firefox (it's 32-bit by default), you should give that a try.  The 64-bit variant of Firefox includes a native NPAPI sandbox, which solves the major architectural inefficiently that leads to the majority of Flash/Firefox instability in 32-bit Firefox.

https://www.mozilla.org/en-US/firefox/all/3