IE 7.0 cookie problem

I have site written in ASP.NET 2.0. Yesterday I've got complains about login problems from my customers. First of all i've checked if site works properly. I was able to login into test account. So problem was not in login implementation.

I've asked customers about web browser they using. It was Internet Explorer 7.0. I was using Fire Fox 3.0. So i've decided to use IE 7.0. I was really surprised when i was not able to login using it.

First idea was that it's security settings proble. I've played around with these settings. Nothing helps. Second idea was cookie settings. This didn't help too.

I've dicided to use havy artilery. I've used tool to see traffic. After some minuts I've found the source of problem. Server has been sending me expired cookie. This cookie was not send by browser during next request.

The source of problem was found. I've to find out why my site sends out of date cookie. The answer was simple. Clock settings were wrong. After system time of server was set to correct time probem has disappeared.

Conclusion: Check client time settings or server time settings to make sure that cookie expiration date is processed by browser properly.