Can't unlock phone unless reboot

Greetings everyone!

I tried a search but it came up dry.

I have a person with an iphone in our organization that recently cannot enter the password on her iphone 3GS with 4.0.2 iOS. When the onscreen keyboard appears the "keys" do not respond. The only way to unlock the phone is to reboot the phone.

Has anyone seen this happen to theirs before?

It happened again on the phone. Phone locks. When I slide to unlock, and push the letters to unlock they do not get entered into the field. I have to reboot the phone by powering it off and then back on in order to unlock the phone.

If this has happened several times, i might try a reset.

Reset iPhone. Press and hold the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears.

It could take more like 15-20 seconds. Don't let up on them too early. Wait for that logo to pop up.

If that doesn't do it, I'd try reset iPhone Settings. Here's the Apple kb article.

Next step is going to be a restore.

Thanks for the tips!! If we encounter it again I will certainly try those steps, doing a backup of the device first, of course!

Thank you very much!