Ubuntu 10.04 with all patches applied,
Qt SDK 2010.02,
Musescore trunk (not branch 0.9.6) rev. 3116

Steps:

1) Start MuseScore
2) create a simple score (in my case: "Test" as title, 1 violin instr., C major key, 12 measures of 4/4)
3) Close it by clicking the 'X' in the tab

Result: Seg fault in qatomic_i386.h, line 120, called (via other library functions) by scoreview.cpp, function void ScoreView::paint(const QRect& rr, QPainter& p), line 1331:

1330    QRegion r1(rr);
1331=>  foreach (const Page* page, _score->pages()) {
1332         QRectF pr(page->abbox());


Incidentally: I noticed the navigator window is now above and the main view below: is it expected?

Thanks,

M.