Just installed C6 on Mac OS X 10.6.6, here the score editor doesn’t crash and opens normally both in new and in old projects so it must be a preferences thing (I started with new preferences).
For me there is one good and one bad news concerning the score editor (you can’t have everything at once;-)
The good news is that there are no accidental vertical lines anymore when you record in the score editor like in Cubase 5, but the bad news is that when you record in the score editor everything sounds staccato and gets also recorded as short notes… AAARGH!!!
This seems to be a long-winded problem because there’s always something wrong with recording in the score editor, in Cubase 5.1 the same error with staccato notes would appear if during recording you were reaching the part boundery and lenghtening it, Cubase would even crash then… then in 5.5 they resolved the crash but there were those annoying vertical lines that came up during recording. Now Cubase does not crash nor produce the vertical lines but it only records staccato notes… I hope they can finally get it right in an update.
But I noticed two other bugfixes: you can delete multiple workspaces at once again and when switching between workspaces with MIDI Editors involved these now stay at their original position again (in 5.5 the key editor would always jump to the top of the screen). Hooray!