Last night whilst driving, I tried moving off and pressed the clutch down. The clutch and gear both engaged but when I let go of the clutch pedal, I felt a locking feeling with the pedal fully down and then it just "fell" back into place. I tried moving off but the engine juust revved and would'nt move. After pressing the clutch pedal, with no slack in it, it reached the section where I felt the click and then the slack came back and worked when I lifted my foot up. I tried enganging first again and the clutch locked itself once more. On my thrid attempt I manged to get the car to move so I pulled over and turned my engine off. I went to check the clutch cable in the engine bay as I thought it could be the "mod" that I made(http://forums.mg-rover.org/showthread.php?t=58806&highlight=clutch+problem), getting caught and not letting to clutch rest again properly, but all seemed fine. What else could it be? and should I be worried?