Opera 9.50 Beta

I had been using Opera 9.50 Beta (Build 1786) for a while (10 days) on the Mac and never had any problems.
However, yesterday I noticed that YouTube refused to play in Opera (on Ubuntu) saying that I needed the flashplayer. However, I knew the most up-to-date version was already there. So why?
Today, Opera just couldn't handle Gmail. Anytime I opened Gmail, Opera just crashed.
So, I updated to build 1800.but no improvement -- still crashing in Gmail.
So then I deleted ~/.opera/opera6.ini and restarted Opera. No more crashing!
Not sure if I can explain this but apparently some config problem was messing up Opera.