Password Verification every so often

[VaShaun Jones]

Listers when I go to mail sometimes I get a message saying I need to  
re[enter my password for my server even though I typed it in  
correctly and saved it in my key chain. It doesn't happen every-time  
I turn on mail or restart or even everyday, but it does happen to  
frequently for me. Can someone please tell me what is needed to make  
this behavior stop?