Happened today. Trackpad and keyboard are "lost". hook up and external, fine. Called, Apple is sending a box to ship it back for replacement. That's the only option.
Happened to me today (second time, can't remember what was opened the first time), I was running parallels, mail, safari and just plugged my iPad in and iTunes opened. FREEZE!
Which USB Port?
I had exactly the same problem as you, left usb port caused it in my case. Right was doing fine tho. Another problem which is known is that Parallels might run into some trouble with Macbook Airs.
The question is if you have used time machine to migrate an old setup of another Mac?
If so you should try installing Lion again. If not there is something wrong with your macbook. Have you looked up the log of your console? Maybe it is really a software wise problem which causes a freeze
Well, try again by plugging iPad out, restart your mac, and plug it in again in the left side. I guess you have the same bug I had. They had to replace a small part on my logic board. If it happens again only on left side you should call Apple and see what they can do
Try a USB HDD or something similar like a USB Stick on the left port and see what happens then.
Yeah well but as you had the freeze on the left port you should try to put the hdd on the left port swell and continue to see if the freezes only occur when you have something attached on one of the usb ports.