Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
This happened to me the other day, not during a call though. I had to turn the screen off and on again a couple times to get it to work.
 
This has just recently started happening to me too. but not just on the slide to answer. sometimes typing a SMS message. Periodic unresponsiveness all over the touchscreen ESP in the ipod app. im on 3.0 non jailbroke phone 3GS.
 
same here...

I got the same problem on my 3Gs that i recieved from t-mobile. Is there any solution to this problem? The iphone sometimes just won't react - so have to push power button so it works again (lock/unlock). Not sure if restore would help.
 
I prefer to use a little WD30 on mine when it sticks, but that is my personal choice...LOL

No Seriously I have that issue when I try to slide the slider too quickly but I use the screen cleaner and I find it works better, sometimes it happens when oil from your finger builds up or that is what it seems to me.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.