I was sent a zip file that contains source code from a CVS repository. All of the source code files are ",v" file extension files. After some research, I read that I needed to install a CVS client and check out the files. I installed TortoiseCVS. However, I cannot check out the files because of an error, "Unknown flag FULL".
I have the CVSROOT set to the top level of my source repository that I was sent. I then use CVS checkout in TortoiseCVS to check out the files in another directory. The fetch list works but I cannot get the files to check out. The first directory is created fine but when it gets to the first file, that's when I get the error.
I've included screenshots of my work for clarity.

I don't know about tortoiseCVS but if you want to recover, I can tell you how to do it on any debian based linux (I think about your problem comes with CVSROOT, so we have to re-init your CVS repository) :
First, install CVS on your ubuntu:
then create a directory to unzip your files:
Then untar the files on this repo:
then delete the CVSROOT directory of the unziped repository.
finally, init your CVS repository another time:
then you can simply checkout the files without a problem with:
Remember that do this checkout out of your repository!
Hope it helps, and sorry if my level of english is not good enough.