Remember when Steve Jobs told everyone that the iPhone 4 had to be held correctly to avoid signal loss and dropped calls? Well, it looks like that same "death grip" problem may be affecting the HTC Sensation. When the Sensation is held in a certain way, it loses signal as well as its Bluetooth and WiFi connection.
According to some tests run by Nordic Hardware, the problem may be caused by the phone's back cover. The unibody design of the HTC Sensation is actually a removable battery cover made of metal and a few plastic patches that function as antennae. If you hand covers one of the patches, the radio performance of the Bluetooth and WiFi are noticeably reduced.
The video below demonstrates how laying the device on your palm, covering the back plate where the antennae are located, can cause Bluetooth audio playback to stop. It's not clear at this point if a phone case, such as what was given for the iPhone 4, will help with the matter.