premiere pro

After rendering my animation i needed to join the 3 renders together using adobe premiere pro. i open premiere, create a new project, in select HDV 720p30, then import the 3 renders separately, drag them into the time line. ensure that the magnet tool is clicked so that the 3 overlapping renders merge together into a consistent video, then click on the sequence tab and select render entire work area. When i attempted to do this the rendering says that's it reaches 6.9% (frame 19) almost immediately on 1/3, then it just freezes. If i click the cancel button then it brings up the loading circle which doesn't get anywhere, so i have to use the force quit option to close the program.