Try updating BrixCC to the latest version, if that doesn't work update the NXT firmware.
Also try re-uploading the code to the NXT after deleting some unnecessary files (demo software, old versions of software, etc.)
"File error" may be a Variable error or file access error, check your code and make sure that all the file access, variables, etc are using the correct syntax and punctuation (e.g. ":" instead of ";")
If all else fails, use the hidden reset button on your NXT (see manual) to format the whole thing.