If CVS is reporting lines as longer or shorter than they should be, there may be a problem with the line-ending conversion from one filesystem to another.
If you are using the ext access method with an rsh replacement, your replacement may be trying to convert line endings. CVS relies on being able to do the conversion itself.
If this is not the problem and the file in question is a text file, you might have binary keyword-expansion mode set for the file. Use the command cvs status filename to show the keyword-expansion mode, and use cvs admin -kkv filename to fix the file in the repository by setting its keyword-expansion mode to the default for text files. If a binary file is corrupted, it might be set as a text file. The command cvs admin -kb filename sets the binary file's keyword-expansion mode correctly, but it might not repair the damage to the local file. To retrieve the original version of the file, use cvs update -r 1.1 -p > filename.