my new htc desire (no added case) has real issues with the proximty sensor and blank screen during calls. I can start a phone call while holding the phone and then place it on a desk with nothing with 6" of it and the screen remains blank. pressing any button or combination of buttons doesn't get the screen back - any ideas or do I need to return the phone for a new one?

I have EXACTLY the same problem.  Everything on the Desire is perfect - EXCEPT everytime I make a call and hold the phone up to my ear, the proximity sensor kicks in, but then after the screen doesn't turn back on - I can't hang up the phone!!

Is there any fix for this please please PLEASE!!  I have a perfect phone...erm...except making phone calls!!

Andy

I've read about people with the same problem getting the phone repaired and then having it work just fine.

For some people simply moving the phone away from their ear (make sure your hand is not on the sensor (upper left of screen)!)

 Others get the screen back by pressing the power

None of this works for me.

I opened the phone - took out the battery to do a soft reset - and made sure the phone id card was really properly seated it now it works just fine!

After more research I was able to fix the problem on my Desire. I have a screen protector which had the smallest tiniest mark on it in the top left.  The proximity sensor is two small dots at the top left of the front of the phone in the black area above the screen (you can actually just about see them when holding the screen up to the sun or a bright light).  

A lot of people apparantly have had this problem when using screen protectors, or cases (I know you said you are not using a case) that cover the proximity sensor.  Once I peeled off my screen protector it started working fine again.

There is an app I used to check when the proximity sensor was detecting something and when it wasn't - the app is called ProxyLightTest. Download that then mess around holding your hand over the proximity sensor and see if it has problems.  I am guessing you might be using a screen protector or there might be a slight scratch on your screen over the proximity sensor that is messing with your signal.  if not then maybe you'll have to send it back.

Hope this helps!  Good luck.

I have the same problem also. I have tried resetting my phone. Ive also tried many apps like call light, shake awake and no lock. My phone is only 5 weeks old and the problem started a couple of weeks ago. HTC and telus wont service my phone since its unlocked and on Rogers.

Same problem here but I've fixed it. Sounds crazy but if you blow in the small gap between the screen and the ear piece it clears dust from the sensor. It doesn't look like there's a gap but my proximity sensor problem fixed itself immediately after I did this. HTC need to seal the screen better to avoid dust getting into the sensor.

Telus was able to send my phone out for repair to a thrid party company. It took about 3 weeks but my phone is working fine now. They had to replace the main board on the phone.  

 Hi where is the id card on the back of the phone this would be a great help[ as my screen goes blank when i phone out but if a press on the back of the phone it comes back on. thanks

FIXED!  I had the usual problem with a black screen when I need to hangup, enter passwords, etc.  I tried the vacuum/blow around the gap at the edge of the screen with no luck.  Out of warranty, I thought I was doomed to wait till I could get a new phone.  After realizing it was useless as a phone in any but the brightest sunlight, I took the dang thing apart (requires a T-5 Torx, a small phillips, and maybe some tweezers).  I eventually got the little board that has the sensor on it out, and found there was dirt (that was apparently immune to the vacuum/blow solution) on the lenses of both the sensor device and the back of the screen.  Cleaned it with alcohol and a trimmed Q-tip, put the thing back together, and voila, it works like new.  There are five ribbon connectors and a coax connector to undo to get to the bottom, but it isn't that difficult if you're careful.  There are six screws on the outside of the back, and a single screw holding the sensor board in place.  Everything else just takes a little prying.  Remove the SD card before taking off the first layer.