Mail keeps reloading

[MAR]

Hi,

Running on XPPro and Win2000Pro

I use Thunderbird to download mail from home and work. I have is set so that the home machine leaves mail on the server but deletes it after 4 days. This has been working fine for a LONG time. Suddenly, on BOTH computers, every time that it checks for mail it reloads ALL the mail EVERY time. So now I am getting multiple copies of the same email.

I had tried Netscape on Linux some years ago and had the same problem.

What can I do to fix this. I can no longer even use Thunderbird. Could this be a server side thing. If it is what do I tell them?????

Thanks