Bug in FTP transfer

Hi all,
since 3 days, I have a strange problem: during the FTP transfer (in FileZilla) of one of my files (CSS file customizing my Drupal-based website), the file that arrives to the destination (dreamhost) is not the same as the one I sent.

The date of the transfer is OK (the time on server correspond to the time I sent the file) but the size is different. In Filezilla, just after the transfer is done, during 1/2 second, it’s correct (e.g. 25.550KB) even on the server, then the server side of the filezilla screen “blinks” and the size changes to 25.115 KB)!

I did some investigation and I discovered that the file that appears on the server is an older version of my file. So in short, I send the new version and on the server appears an older one (I even created a new folder and sent the newer file to the new empty folder… and what appears? The older version!)

Until now, it never happened… Any idea? I really need to corect it, as my website layout is heavily disturbed by the use of the inappropriate (old) CSS file.

Thanks in advance for your help.

I’d try opening the serverside file, pasting in (overwriting) with the new CSS content, save it, and see what happens.