Connecting to MrFreake's stock sandbox dev server, clicking the Launchpad dialog and then attempting to click any ship generally locks up the dialog and the whole application. Perhaps this is due to an abnormally high number of Kerbals? (2345 on this server.)

Should be fixed via 6a1a5bc

It's definitely caused by having thousands of kerbals.

You're definitely correct about that, I get this too.

The workaround to this is to launch from the VAB or SPH, but I always forget. This one is getting fixed today (By marking all kerbals available so they stop getting generated)

Confirmed. There is a small pause (2-3 seconds) when the dialog loads but that might just be stock KSP. This is on MrFreake's stock dev 6704 server.