Openshot and system irregularly freezing.

Hello everyone.
I am using Openshot in Mageia-2 (fully updated).
The video clips are fairly lengthy and I am clipping them and joining up.
The App and system seem to freeze up regularly during the reviewing and clipping stage and I haven't got to the final joining up stage.
The box has 8Gbs of DDR3 memory and what I think is a reasonably fast video card.
Plus it is using an Intel 64Gb SSD as the Root and Home drive and and all HDDs are Sata3.
Is there something I am missing in all this. Note all the video clips are on a HDD in a USB3 Dock.
Is the Video card likely to be inadequate or is it something else.
No other Apps freeze or are there any problems when using the machine for anything else.
Any suggestions are welcome.
Cheers. John.
I am using Openshot in Mageia-2 (fully updated).
The video clips are fairly lengthy and I am clipping them and joining up.
The App and system seem to freeze up regularly during the reviewing and clipping stage and I haven't got to the final joining up stage.
The box has 8Gbs of DDR3 memory and what I think is a reasonably fast video card.
Plus it is using an Intel 64Gb SSD as the Root and Home drive and and all HDDs are Sata3.
Is there something I am missing in all this. Note all the video clips are on a HDD in a USB3 Dock.
Is the Video card likely to be inadequate or is it something else.
No other Apps freeze or are there any problems when using the machine for anything else.
Any suggestions are welcome.
Cheers. John.