So last night, making a sweeping left (intersection, no traffic),dry. I stepped the rear out for the first time on the RX330. new tires, about 10k miles on 'em. Music was on so I couldn't hear the beep, and I don't think that light showed up on the dash. I've had other AWD cars before and LSD.

Not sure how fast I was going maybe 20, but it broke loose mid turn. Behaved well, off the gas, and traction came right back, just wondering under what conditions you had the rear slide on you.

 

My only experience was during freezing rain doing a sharp right turn off my street with my foot a little throttle hungry. Guess I hit a patch of black ice. Back broke loose and traction control was lit up and beeping like crazy. But immediately regained traction after letting off the gas.

 

I went through some pretty horrid winter conditions the last 2 months (ice & snow) here in the Great White North with no sliding issues whatsoever...
then again, I do not drive the RX330 as if I stole it, as a particular CL member mentioned in another post recently.
LSD?, my fond memories of the late 60's. Professors in university would actually make it for us for free to make sure we do not consume any bad stuff available on the streets.

 

Ive had mine come on a few times, but only in icy conditions (I live above 10,000ft in Colorado). Never when it was dry. Maybe you ran over some oil or residue on the road? Mine's an 07 and it feels pretty planted. Lexus claimed when they came out with the 07's that they put the "viscous coupling controlled, limited slip diff" into, plus 50/50 power distribution between front and rear wheels at all times and I can definitely feel power in the rear wheels under all conditions. In 08 through current models they went to "active torque" system which only powers rear wheels once slip is detected. 07s have a few more glitches having first introduced the 2gr, but it's worth it having a more robust AWD system IMO. Mines a tank in bad conditions too, ice, snow, hills, nothing stops it.