Anyone else having this issue? I see the screen have a horivontal flicker from time to time, primarily when dark grays are being used on apps or the browser.
is it software or hardware?
Yeah, this is a new one.
You could also attempt booting to Safe Mode as well, see if that helps.
Restart phone. At first White Boot Screen, press and hold the Volume Down button until fully booted. You should see Safe Mode in the bottom left corner of the display when it's finished booting.
I did a little research and found that if you have an overclocking app installed on your EVO, it could be the cause of the problem. Let me know if the device reset or safe mode troubleshooting worked.
If it's an overclocking app, this should stop then when either the Factory Reset or even Booting to Safe Mode is executed. Of course theres always the possibility that it's messing with a core function in a way that prevents the Safe Mode from doing what it's supposed to. In that case, the best way would be a factory reset.
It's easy enough to determine. Boot to Safe Mode. If the problem persists, then something that was installed has messed with a core function in some way. To cure that, you would need to do the Hard Reset. An example of this is an issue people are having where every once in a while the phone just starts rebooting on it's own. Booting into Safe Mode should prevent a 3rd party app causing the issue but the phone even rebooted while in Safe Mode. Performing the Hard Reset however stopped the rebooting completely.
I know this because the example above is what happened to me.
I've never had any over clocking apps installed. Issue still occurs on occasion. As I stated earlier, its random. Only seems to effect areas with deep gray colors, but not blacks or whites. I've seen threads of the same issue on the HTC forums. Factory reset doesn't fix the issue, still occurs at random. Seems this is something I have to live with along with not having custom ringtones. If I knew these issues existed I would never have gotten this phone.
If you have the insurance, I would take the phone into a Sprint Repair center to be looked at and possibly replaced. Keep in mind, fist thing they will do is a Hard Reset to verify for themselves that that doesn't fix the issue. If the issue continues, you can usually end up with a replacement phone.