I have this same issue, but it's with the bottom row (the dock) of my iphone, so I can't go to phone/texts/safari/ipod, and I cant slide to unlock or answer any calls. SO ANNOYING.
I read this online, which you apparently did too:
"This may help:
RapidShare: 1-Click Webhosting
This is the General.plist file that adds a touchscreen setting to your General Settings. It can alter the touchscreen sensors, with 0 being a high sensor (which is what I have set mine to now) and 16 being the lowest sensor (can't move anything). Default setting is 3.5.
Upload the file to Applications/Preferences.app and you're set!
Best,
debu@hot.ee"
How do I do this? I really want to try this in hopes of fixing my iphone, because it still RARELY responds to touch, although it sometimes does...so there is hope.
Any help is immensely appreciated!