Flaky brakes and new tires slipping, squealing

[HoyaTerp]

<groan> I did a couple searches and didn't come up with exactly what I'm experiencing. So I'll post my woes here and maybe someone here smarter than my dealer can help out.

I had the two front tires replaced less than a month ago (Diamaris, rear are fine). Almost immediately upon picking up the X from the tire shop, weird things have been happening:

1. Rumbling/rubbing noise from right front wheel well.
2. Sqealing, slipping, and almost a "hopping" feeling from the tires when turning corners even at moderate speed.
3. Brakes grab at quick low-speed stops and seem to fade at moderate-speed abrupt stops. In other words, a recent panic stop at 40 mph felt like I just had coaster brakes and I nearly rear-ended somebody. (Pads/rotors replaced last May, about 10k miles ago.)

I took the X into the dealer this week and they fixed #1, which was a loose underside wheel well panel. Fine. As for #2 and #3, they thought I was nuts. Two mechanics test drove it and could find nothing wrong at all. Brakes are in good shape and a dump of the OBC showed no fault codes.

On the way home just before writing this, I make a left turn onto my street at about 15 mph and the left front wheel starts slipping and chirping through the turn. It's getting scary.

At this point, I don't know if the dealer overlooked something serious or if the tire installer may have done something. Maybe the new tires are no good? Or am I just nuts? Whatever it is, it's a safety issue.

Thoughts, anyone?