What can be the culprit? Virtually anything. I once had an issue where I started out with a RAM test... passed as "OK". I eventually swapped out everything except the MOBO and still couldn't get it. Turned out to the RAM... even though a RAM test had tested OK. Waaay aggravating.
Sounds like connector issues or the bluetooth stack is having a problem. Consider: using an emory board or 000 steel wool and clean BOTH sides of the connections. For the Bluetooth just do a remove all items and re-add them. Or remove Bluetooth and reinstall. Bluetooth stacks, especially older version are notorious for getting corrupted. Seems like you are in computer hell and more in the IT business than trading business. So sorry. BTW: you don't have an Ozone air purifier in the room do you?
My rig was setup in Sep 2011. The motherboard is Asus P8H67V and i7 2600. It's about 13 yrs already and it's running fine(touch wood). I am recommending to you my true and tested method. Just spray the crap out of the problematic contact and it will be OK. In my case, it's the RJ45. My area is very humid.
First I would like to express my deepest Gratitude to all of you for taking time to suggest various tips & tricks. I completely forgot that I have another new workstation with a shitty keyboard with almost no edges. What seems to be the culprit is the keyboard itself. I tried to pull & push the wire going into keyboard & it makes that connect & disconnect noise. I looked on the back of the keyboard to see if I can open it to fix it & the number of screws is mind boggling so I have ordered 2 new keyboards to be on safe side which will take time but until then I think I will be able to put up with this one. So Thanks to everyone.
If your keyboard is the expensive type with mechanical keys, then it is worth repairing it. Open up the keyboard, and Look out for poor connection/broken solder joint.