"Sony Screen Freeze" happened to me within a couple hours of purchase at a Best Buy in Canada.
Here's my experience:
I hadn't yet loaded any new books on it, and was just trying out the reader with the pre-loaded material...screen froze up seemingly for no reason.
I just put into sleep mode and went on with my day(no powerdown or hard-reset)... Next day, woke it up and it was working fine.
...weird.
Firmware update please!!!
Too bad the T1 isn't made by RIM...it would receive negative headlines in the news everywhere - and maybe we'd hear something from them in acknowledgement.