VideoStudio :: X3 Won't Open Files 1GB And Above

The previous problem I had was it wouldn't smart proxy 1GB files and above (still not fixed), now X3 won't open files 1GB and above. I tried opening files over 1GB that I have edited before, but it's not happening. Basically the files are from a Canon 5D MKII, converted to AVI via Cineform Neoscene. Today I selected about 12 clips I have just converted to AVI I filmed yesterday, and 4 of them (over 1GB) gave the following message

".... file is not accessible"

then

"these files cannot be added to this project. These files may be of unknown file format. The computer does not have enough memory, or the file is coyright protected"

Is there some restriction setting I have accidentally selected? Like I said this is a new problem, these files would open before. I've tried clearing some space on my laptop's hard drive, so there's over 200GB, but that didn't work either. I contacted Cineform, and they said their file format is the same whether it is above or below 1GB in size, so the problem lies with Videostudio.