What version of the program are you using?
What operating system are you on?
If your project stored on your C drive or on a second or external drive?
What model of camcorder is your video cominng from?
How much free, clean, freshly defragmented space is on your C or main drive?
Also, when you attempt to Open that Project, what exactly happens?
Do you get any error messages, and if so, what is the exact text of those messages?
What Project Preset did you choose, and did you Save that Project, after you created it?