Inspiron 1525 doesnot shutdown

I have a inspiron 1525 which i bought about 21 months ago.

Config:

          Core2Duo 2.0 ( T7450)

          2.5GB DDR2

          Intel GM965 chipset

          Windows 7

The battery was dead around 3 months ago and i have removed the battery. Now running using adapter. Now when i shutdown, hibernate the machine it restarts. 

Is there anyone who can help me???????????????????????