Why is Citibank tossing my cookies (browser question)?

Factual Questions
1

I do my online banking with Citibank. The first time you use the site, you sign in, giving a userid (unique to your machine), your Citicard number and your PIN. Thereafter, it’s supposed to remember your citicard number when you enter your userid, so you only need to enter your PIN next time.

Well, this works for a while (usually a week or two), then the site “forgets” that I had previously entered my PIN and I have to start all over. This has happened in both Netscape & IE, on NT, Win2K, and Win98. Citibank tech support couldn’t give me a reasonable answer on why it was happening, other than saying their cookies were getting corrupted. One tech wanted me to delete all my cookies, because she said that Citibank had so many she couldn’t give me a list of which onces they are (and they don’t all say Citibank in them, apparently). Another suggested that it was happening because I wasn’t specifically signing off when I was done with the site; I tried being vehement about doing that (not that I believed them, but I figured I’d humor them), but it didn’t help.

I don’t think it’s me. Help!

2

Well the cookie probably has an expiration date in the near future. When you log in, it probably refreshes that cookie and sets a new expiration date.

Does this happen when you don’t visit the site for a few days? I wouldn’t think the cookie is getting corrupted. If, for example, the expiration date was set to expire in 2 days, and if you don’t log in to your account before then, then the browser will delete the cookie itself, requiring you to recreate it by entering all your information again.