318 - dodgy rear end!

 Okay, the wifes got a 318 se (2000 'x' reg) . On a couple of occasions  whilst going round corners  ( at normal speeds with the traction on!) the back end has flipped out quite severely. It has done it once when I've been driving. The rear tyres have plenty of tread left but there seem s to be a creak coming from the rear suspension. Cars done 83000 miles.

 Any ideas what the prob. is.

Cheers.

 I think it was more likely to have been 2nd gear. The tyres are Michellin Energy and the pressures were checked about 2 weeks ago to manufactureres recommended pressure. They both seem to be wearing fairly evenly, too.

 I seem to remember that some suspension components were replaced under warrenty at approx. 40k miles but I think that was the front!