rattling

Hello, I purchased this cooler 21 months ago. Now it has started making rattling at high RPM. Whenever the fan reaches 2400+ rpm, rattling starts. Now if i touch the fans side, rattling goes away for a while then comes back. After this point, fan rattles at >= 2000 rpm OR when fans RPM falls...

I recently bought a PC with the following configuration: 1. Athlon 64 3000+ (939) CPU 2. 256x2 400MHz DDR RAM 3. 80 GB SATA HDD 4. MSI-RS480 (IGP) Mobo 5. Combo and FDD 6. 17" Flat CRT 7. WinXP+SP2 Earlier, I hadn't heard the loud rattling sound given out by the FDD on Windows logon...