Thanks Camstuf. I didnt have any screen protectors.
Surfed around and found that I wasn't the only one with the issue - apparently it impacted a subset of devices. I found an HTC test code on another forum - posted by HalcyonCMDR123 - am copying and pasting the recommendations here - it seems to be working after i ran the test. A direct link to his post is also below...
This could be related to the proximity sensor itself, not necessarily software. You can test the sensor by going to your phone dialer and typing in *#*#3424#*#* and choosing ACCEPT. Choose "P-Sensor" in the list and press RUN. Follow the instructions on screen. It jsut has you cover the upper section of the phone (where the proximity sensor is located) to test if it works properly. If not, it likely could be your proximity sensor is damaged or otherwise having issues. If that is the case I would recommend taking it into a local Service and Repair location to have the techs check out your phone.
Also, if you have a screen protector on your phone, esnure it is not covering the proximity sensor. It is located just below the far left edge of the speaker grill at the top of the phone. You can see the light difference where the hole through the screen bezel is for the sensor to operate.
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