I've had problems with LibreOffice freezing for years, but this is the first time i've ever been able to consistently reproduce it.

I noticed it was constantly locking up when a new piece of code was running in the background. After some testing i've narrowed it down to the following relevant bits:

---------------------------
for (int i = 0; i < 10000; i++)
{
	try
	{
		string html = "HTML Text"; // html content
		WebBrowser wb = new WebBrowser();
		wb.Navigate("about:blank");
		wb.Document.OpenNew(true);
		wb.Document.Write(html);
		wb.Document.ExecCommand("SelectAll", false, null);
		wb.Document.ExecCommand("Copy", false, null);
		System.Threading.Thread.Sleep(100);
		wb.Dispose();
	}
	catch (Exception ex)
	{
		int j = 0;
	}
}	// For Loop
---------------------------

This is obviously not production ready code and is intended for demo purposes only. But approximately three times out of four when I start running this C# code in Visual Studio 2012 LibreOffice will freeze up after 5-15 seconds. It will remain frozen until i either terminate the code or it crashes. Most of the time LibreOffice will then return to normal behaviour after that, but occasionally it will remain stuck.

I've mostly been testing this in Calc since that's usually what I'm using when I observe the freezing behaviour, but during testing it also affected Writer.

No other programs seem to have their basic functionality affected when this code is running. Excel performs normally, Word performs normally, Outlook, Chrome, Firefox, Notpadd++, everything else performs normally.

However copy/paste is impacted on a global level. (Not entirely unexpected given the code's use of "copy".) Notepadd++, Word, and Excel all have intermittent issues with trying to copy/paste text while or immediately after this code is running. But as long as i don't try to copy/paste anything they continue working normally. LibreOffice is the only program to become generally unusable.

Since i frequently observe the "normal" LibreOffice freezing behaviour while trying to copy/paste cells in Calc i'm really hoping the fundamental underlying issue is linked, and if you can resolve the issue in this exceptional case it will fix the other more common case as well.