Problem/bug with CVS

I have the following:

Client: Concurrent Versions System (CVS) 1.12.12 (client)
Server: Concurrent Versions System (CVS) 1.12.13 (client/server)

I have a new problem with cvs where it is not committing or updating my 
files correctly.  I checkout the project correctly, make some mods, and have 
done the modify commit modify commit loop a number of times.  Things changed 
for me today and I am currently stuck in a loop where 'cvs update' will 
repeatedly update the file (either 'M' or 'U' status) and 'cvs commit' will 
complain that there are outstanding conflicts.  There are no conflicts. I 
created a new sandbox, and (with no changes to the files) did 'cvs update' 
and 'cvs commit' with no problems, then made some benign but obvious changes 
to the files and the same thing happens there too.

Unfortunately I lost 1+ day's work because 'cvs update' trashed my changes 
in some delicate code.

Two questions:
(1) What is wrong with my sandbox and/or repository?  Hopefully this is a 
known problem with a simple solution.
(2) Are the day's file changes truly lost or are they hiding somewhere?