Over the past few days I've developed a very odd problem in my manual gearbox W124. After sitting in stop start traffic for a while, the car develops a sort of high pitch whine. Once this whine starts, in a seemingly random fashion, the clutch pedal sinks to the floor and the clutch doesn't disengage. If I get a toe under the pedal, I can lift the pedal back up and on the second or third try, it works... for a few minutes before it does it again. As you can imagine, this is really scary to drive like this. When the engine is not hot, the clutch is fine and there are no noises. Both the clutch slave cylinder and master cylinder were replaced yesterday, still the same problem. I'm now assuming something untoward is going on inside the clutch housing but I'm somewhat baffled as to what it could be and I'm very reluctant to take it to any clutch specialists as Its likely they'll just throw in a new clutch and potentially not fix the underlying problem. Anyone experienced similar or may have an idea what it is? I'm really not looking forward to doing this job, especially without a ramp.