Hi Sarah -- and welcome to the forum. I'm sorry it is not in better conditions for you.
This statement mystified me a bit:
I have installed the Corel Videostudio pro x4 codec and that hasn't helped at all.
I am not really sure what you mean by such a codec. As far as I am aware, there is no such thing. During the installation of X4 as a package, some codecs are installed, and the program otherwise uses whatever other codecs are already on the computer either installed by you or as part of some other software package.
And this is where I suspect your problem lies. You say you are trying to open an AVI file, but what kind is it? You see, there are over 800 different video formats which call themselves AVIs. The extension .avi in other words is just a wrapper. Pure uncompressed AVI is huge, taking around 65 GB for one hour of video. At the other end of the spectrum are highly compressed mpeg-4 type formats which are very much smaller. An entire 90 minute movie can be compressed to around 800 MB. The fact that you say your video is high def makes me suspect it is one of these latter type formats, such as DivX or XVid.
The fact that the video will open on your laptop but not your PC also suggests that you have the relevant codec on your laptop but not your PC. But first we need to know exactly what format we are talking about. Since you can open the video on your laptop, even if it is too slow in VS, can you please nevertheless insert one of the video files into the VS timeline or library window on your laptop, then right click it and copy ALL its properties here. And it doesn't matter which version of VS is on the laptop -- the Properties will still be the same.
If indeed it turns out to be either XVid or DivX, and you know you have not downloaded and installed either codec on your PC, then you can go to the DivX.com and download the free community codec from there; or else Google for the XVid codec. Hopefully, that should change things for you.