Clutch or transmission noises I dont know? Help.

[sittinsideways76]

3 days ago it happened for the first time, When im holding down the clutch and slowly start to release it I get a sudden short but loud vibrating noise, it almost makes the sound you hear when you grind a gear but maybe a little more high pitches than that. now it happens maybe 1-3 times a day and only happens when the lutch is down and being slowly released from a slow to stand still position, I know the clutch is kinda old and stock (can not powershift because clutch will not grab). Anyone know what this means or have this problem?