Whenever I select "mark prior opened" in the message menu my phone just freezes and i have to remove the battery and wait while it resets. WTF?

How many emails are we talking about to mark as opened? It can take a while for the handheld to do that much work if there are a hundred emails to open. I know if I do a delete prior with a lot of emails, it can take up to a full minute. Doesn't sound like that long but when you're staring at an hourglass it's a long time. I've not used the "mark prior opened."