http://boardsus.playstation.com/playstation/board/message?board.id=ps3&thread.id=898874
If you are having trouble with a headset after it is paired with the PS3, there are a few things to check first:
Make sure your headset battery is charged and working. Be aware that some brands/models will need to be paired again after each recharge. It's not a problem, it's just the way those models work.
Make sure your controller is charged. Lots of strange things happen when the controllers don't have enough power, like dropouts and headset interference.
The headset should be set as the input/output device from the XMB.
For Bluetooth users, make sure there are no other Bluetooth devices in use near your PS3. Also try to eliminate any other radio frequency interference if possible.
For USB users, make sure the connection is secure and there are no wire breaks.
Update your console to the current available firmware.
Pairing Problems:
If the PS3 cannot locate your headset, make sure that your headset is in pairing mode before you start scanning. The headset instructions will tell you how to set yours to pairing mode.
If your headset is missing from the device menu after you re-start your PS3, you will have to pair again. Many headsets will only "remember" one device at a time, so you may have to register again after using your headset with a phone.
If your headset appears on the Audio Device menu but is "grayed out" or not selectable, it is not connected. Make sure the headset is charged, and that it is on in standby. I should connect automatically when the Audio Device menu is selected. Tap the call button on the headset if it does not connect, or click on the Connect Bluetooth tab on screen.
Make sure no other Bluetooth devices are in use nearby.
Headset-Controller Interference:
If your controller loses contact every time you turn on your headset, they might be interfering with each other. If the game allows it, changing the controller port assignment might help. To change the controller port assignment, hold down the PS button while in game. The settings screen that comes up will give you the option to change the controller port. This will have to be set each time you restart your PS3.
Be careful if you walk out of range with an active Bluetooth headset. When you return you will probably experience a controller lockup as the PS3 tries to acquire the headset signal again. Put your headset in standby or just leave it near your PS3 if you need to move more than 30 feet away.
And, as always, make sure no other Bluetooth devices are in use nearby.