I tried the app for the first time today. My phone language is German and my timezone MESZ (which is UTC+2). I looked into the wallet data file in the app directory with Root explorer and found the date format that is saved. Sat Aug 06 13:22:09 MESZ 2011 is an example.
Also it seems that the force close might be triggered every time the app tries to load this file. I noticed that an initial update isn't necessary to get a fc. Restarting the app after importing the addresses has the same effect.
Yes it's definitely related to the way I store the date in the file, I was already planning on changing it to a unix datetime this weekend based on the a few bug reports from 3 Aug (identical to yours) so it should solve the issue. When I set my timezone/language to German/+2 GMT I could replicate the FC as well. Thanks again for the detailed report.
Edit: in my defence, arguably this is a bug in Java Date... I was assuming that date.equals(new Date( date.toString() ) ); but obviously not...

Will