unable to access a disk space after partitioning in windows vista

hi,
I have partitioned C drive of 141gb using disk management console into 3 drives. one is F drive of space 20gb and second is A drive of space 46 gb and another is 75 gb .
I have to used patiton magic to repartition it.
but now i am facing a problem the two drives A and F are visible in disk management console,but not visible when i open my computer icon to see drives .When i tried to access them in DMC a window is opening is opening showing the error that DMC is not up to date.my hard disks total size is 160gb, but I am to see 150gb only .please any one help me to solve this problem .Kindly reply