Problem opening project in latest preview

Hi, I was able to open a project in preview 7 previously, did some worked, PC crashed, opened backup version that I saved over the original project, and now I cant open the project with preview anymore. But I can open the project with 6.7 and work without a problem. I am getting this error on on filetexture nodes:

When I remove these nodes, vvvv freezes and does not do a thing.

after working more and saving this problem just disappeard but ill keep an eye if something like that happens again