Lion Mail needs to keep inputting passwords - what is up with this?

My 13 MBP Mail client keeps wanting me to input paswords - sometimes as many as 5 to 6 times. It is a real pain in the neck. Also,it also does not seem to reliably remember my email account passwords. I have 3 comcast POP email accounts and 2 Gmail accounts. My separate MS Exchange email is working just fine relative to Office 2011 for the Mac. I migrated my email settings over to this new MBP from an older MBP running SL about 6 months ago. The Lion Mail client has been buggy ever since. My MBP is fully updated. What is up with this? Does the Kychain need to be cleaned? Anyone else have this problem? Please advise.