wincvs "try 'cvs login' with a real password"

I can't believe sometimes.. small things can frustrate you so much!!!
Today I had a problem with WinCVS:
In the past I checked out a module from CVS with a collegue of mine user&password..
so then I changed the WinCVS Admin log-in with my credential..
and so far everything was find: I could log-in without any error.. but there here it begins the nightmare: whatever I was trying to do on my old checked out module I was getting this error:
"Empty password used - try 'cvs login' with a real password"
even if I was logging-out and logging-in again with my real and correct password!!

so anyway.. making the story shorter.. the problem was that the folder where the project was checked out.. contained, in each hidden CVS subfolder, a file named 'Root' that still had the old credential written on.. and this was creating a conflict!!
So then to solve the problem, as you can guess, I had to do a find&replace on all the module folder.. changing the old string credential with the new one..
... and, guess what???, IT WORKED.
such a nightmare.

Hope to help somebody with the same problem.. because I couldn't find much online related with this issue.

See you guys ;)