It is possible that the appearance of the problem coincides with a particular browser update - the problem is so inconsistent that it is difficult to be certain when it started. I have only one extension installed (relating to YouTube). I am happy to try v12.16. From what I've been reading about v15 (now that I know it exists), I think I will be staying away from that for a while. I have Firefox installed here too, I just don't use it very often, so I can try that if the problem recurs in Opera v12.16.
I will let you know what I find out ... but don't hold your breath waiting, it may take a while to be confident of the results.
