Partition Magic help

[bm23]

im trying to create another partition on my hdd using partition magic 8. when i click finish, an error pops up, saying "Error #2103 Partition of specified size could not be created". i have 2 drives, C and D, with 145gb and 87gb of free space respectively. when trying to create the new partition, i choose to make it to be 20gb. also, there are a few unallocated space that is 0mb in size. is that normal? here's a screenshot.

 

[bm23]

update: i tried doing chkdsk in read only mode but it came up with an error during stage 2 of 3. something about error found and cannot continue in read only mode. i also did the normal chkdsk but i was away during the completion of stage 5 so im not sure if the chkdsk completed properly.
did some reading and it seems that those unallocated space are the problem. that's all i got. tbh, i have no idea what they all mean. any help would be appreciated.