The MC13 beta build is actually fairly stable. Crashes relating to JRTools.dll are usually related to the Windows Explorer integration (adding MC to the Windows Explorer right-click menu).
Have you tried rebooting? Often that fixes JRTools.dll issues. If not, try uninstalling, rebooting, installing from scratch, rebooting again, and then try running it.
If none of that works, we'll need to look at your logs.