When you got the message to replace the corrupt file, did you check yes?
Firefox is set by default to download files to the desktop. I go there to delete the corrupt file.
Also, there may be a problem with the particular site that you are downloading from. Firefox and Thunderbird are available at many different sites. I prefer using the Mozilla site. Try another site.
Best of Luck
I just got rid of Internet Explorer 7.0 which was a mistake to download to start with and recently downloaded Mozilla Firefox which I really am liking. I have now decided to convert Outlook Express to Mozilla Thunderbird. I have tried 4 times to download it. The file states it just over 6mb. Each effort to download starts out ok and continues until it completes just over 3mb at which time it indicates the download is complete. Then a window pops up that states run at the right top and has a cleanup button at the bottom. When I click run I get a window message that the file is corrupt. Each additional time I attempt to re-download the program, I get a message, "file already exists, do you want to replace". I downloaded Firefox without any problem but it seems impossible to get Thunderbird. Any suggestions would be appreciated. Also I am on dial up if that matters. Its always worked in the past with a lot of patience. I 'm running Windows Xp, home edition. Thanks in advance...Jim