Win 2003 D Drive is Full but Data is 50% Only.

My windows 2003 Std 64 bit server’s hard drive is 200 GB, divided by two partitions

C= 50 GB (Primary Partitions)

D= 100 GB (Logical Drive)

OS install in C drive our main oracle database installed in d drive, my problem is D drive is getting full. but my data is only 50%. Please help me how can I get the D drive remaining spaces………..?

Thanks & Regards

Trimurthy