Mur21

I have a 300gb hdd that i installed recently. I separated it into 2 partitions. I wasn't sure if my computer would be able to deal with a partition over 130 so i made the second half of the drive about 150gb. After I started putting some movies games and music on it it would begin to crash and reload the desktop, closing the folder i was in. I tried moving some of the files to the other partition but it was still happening there too and the drive is 127gb.

I wanted to know if I went into the disk management setting and deleted the second partition would i be able to reset it to less the 130 and create a third partition with the remaining or do i have to erase the entire drive and start over again.