Default G1 touch screen problem.

Had my G1 since day one. my touch screen is way off every once in a while. And sometimes can't even select stuff on the screen. I reboot the phone and it works again until my phone hearts up from me using it. Then problem comes back. Could it be a software problem? I am hoping not hardware. Is there anyway to reset it or calibrate the screen? Or art least tell what the problem outs? Thanks
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__---Current---__

Phone: Nexus 5 / iPhone 4S
Tablet: ASUS Transformer prime / Nexus 7 /iPad 3
__---Past---__

---Phones---
G1>Bold>captivate>surround>infuse>iphone 4>nexus S>vivd>iphone 4s>galaxy note>Galaxy Nexus>Nexus 4>Galaxy Note 2>Nexus 5

---Tablets---
HTC flyer>Asus Transformer