Not even sure these forums are monitored, but I have the same issues as you plus navigation/maps crashes/locks up every time it's used. Post Jelly Bean. Have done a hard reset, twice, with no luck.

Same issue here. It bugs me so bad.

I am having the same issue about the proximity sensor. Have you gotten any reply for this bug?

Same problem with proximity sensor on my phone and Husband's. Extremely annoying!!

I'm experiencing the same issues. Anyone have any more info?

I was having the same issue until I fount the following solution on the sprint forums:

“What you will need to do is to clear the cache partition from the phone, if the phone allows you. Make sure your phone has the battery fully charge. Wiping the cache partition will get rid of some of the temporary files your phone is holding on to. These files can occasionally store corrupted data which can cause loop rebooting. You will need to have the phone in the Recovery screen, to get there, with the device powered off press and hold the Volume Down and Power button, you will see the android logo and wait until you see a menu > Navigate to “Recovery” using volume buttons > then press power to select > wait until you see an icon of a phone with an exclamation mark and a triangle, as soon as you see it, press and hold volume up then press the power button > Navigate to “Wipe Cache” > Navigate to “Reboot Phone”.

HTC

Proximity sensor works correctly now.

I was having the same issue until I fount the following solution on the sprint forums:

“What you will need to do is to clear the cache partition from the phone, if the phone allows you. Make sure your phone has the battery fully charge. Wiping the cache partition will get rid of some of the temporary files your phone is holding on to. These files can occasionally store corrupted data which can cause loop rebooting. You will need to have the phone in the Recovery screen, to get there, with the device powered off press and hold the Volume Down and Power button, you will see the android logo and wait until you see a menu > Navigate to “Recovery” using volume buttons > then press power to select > wait until you see an icon of a phone with an exclamation mark and a triangle, as soon as you see it, press and hold volume up then press the power button > Navigate to “Wipe Cache” > Navigate to “Reboot Phone”.

HTC

Proximity sensor works correctly now.

My phone has turned into a useless brick after the Jelly Bean update. Google Maps, Chrome, Any Internet Browser, Gmail, Gallery, Android Market and countless other things crash whenever I try to open them. Also, my performance is severely hampered — sluggish speed on overall performance. I've tried your fix to see if it would work with my issues but did not!

If you are a sprint user call tech support and they will walk you through the fix

Only solution so far is a factory reset. This is the answer I received from both the in-store employee and the tech guy over the phone.

Same issue with proximity sensor.... except that even when I turn the screen back on with the power button, it turns off again when I touch the screen anywhere... This bugs the crap out of me when I'm on the phone and need to lookup an email or something.

Im sorry to hear the update is causing u these issues, i would advise to try clearing the data in cashe in the recovery mode. To do this what you will have to do is:

1. go to your settings and then select power, at the bottom there is a option called fastboot, uncheck this.

2. Press and hold the power button until you see those airplane mode, restart and power off, tap power off

3.press and hold the volume down button then tap the power button, You should be on a screen with 3 little green androids on skateboards, with a screen that has hboot and recovery along with some other options. Use the volume down button to go down and highlight recovery, then use the power button to select.it. The screen should change to have a picture of a phone with a ! in a triangle. wait about 30 seconds

4. Press and hold the volume up then tap the power button, The screen should change to have more options pop up like reboot system now, wipe cache partition, and wipe data/factory reset, when you see these go down and select wipe cache partition then hit power to select.

5. Go down to reboot phone with the volume down keys and then tap power to select.

your phone is going to power off then start up again, Hopefully this helps, it doesnt remove personal data so your items on the device will be ok.

Thanks for the suggestion from Madpuffs.  I followed the steps, however it did not work.  The screen still goes black during phone calls and voicemail after the Jelly Bean update.

A Clue

But, I believe I have discovered how to easily recreate the issue.  If in a building (eg my office desk), the problem occurs.  If however outside during bright sunlight, the phone call and voicemail work fine (e.g. turns on and off perfectly just like ICS). 

As an additional test while outside, I held my hand over the proximity sensor and the screen went blank, and when I removed my hand the phone / voicemail screens returned.  Thus it appears that when inside a building, the proximity sensor doesn't adjust for lower lighting.

Hope this clue helps.

UPDATE: here is a simple workaround.  Shine a flashlight (I have a small one for hiking/camping) on the proximity sensor.  When I do that voicemail and phone dialer work fine.

Also, per an email by HTC tech support, this is a hot issue and has been given priority status.  But no release date yet for a fix.