Has there been any changes that you know of in your security software, the most common reason for not being remembered is that your cookie that holds your logged in information is being deleted when you close the program. Sometimes privacy management software will delete these cookies in its attempt to protect you. We also have been having a problem with login and registration that only affected a few people, it has been corrected but this could be part of that issue.
I think when I run a scan using my security software that it is wiping out my cookies. I have to sign in after running a security scan, but that is the only time (unless I have been off for a long time).
I run "Ad-Aware" daily. I found out the hard way (wiped-out cookies and history) that certain settings in Ad-Aware will wipe out cookies and history. Every day, I was having to input everything again - until I discovered what was happening.