I was going to post a question, but I (think?) I have found the solution (For once!)

Firefox for opensuse has auto updated itself to 3.6.8... OK, but now if I click a link, it opens in a new tab NEXT TO THE CURRENTLY OPEN ONE. I am used to the new tab opening as the last of the open tabs, ie on the far right. Nothing refers to this in the edit>preferences AFAICS.
However in about:config, there is a key I can set to make it behave like it used to:

browser.tabs.insertRelatedAfterCurrent, set this to FALSE and Bob's your Unc

HTH somone else