I don't have Roxio, but it appears that your problem is well documented and that this particular software is not ranked very highly among its users. (See CNET.com rankings).
Assuming your computer is properly configured, you're not likely to have these issues with any other NLE program.
Don't give up on computer editing programs. There are plenty of people doing great stuff with inexpensive software like Sony's Movie Studio and Pinnacle's Studio 9.
Aside to "svhs" - you do not need a Pinnacle card (DC-10, etc) to use Studio 9 with a digital camera.