Can't login to Magento admin

Question

I have magento installed in a subdirectory. www.domain.com/subdir/magento

This site worked perfectly at one point. I changed nothing, until my client said he could

Answer 1

I had the same problem, but I was working on XAMPP on windows 7 x64.

In Magento system - configuration - web - session cookie management change Use HTTP Only to no and Cookie Lifetime to 86400.

I only changed the Cookie Lifetime just in case of daylight saving time may not have to be changed.

Before the changes I could only login using Firefox and after the changes all browsers work.

Leave Cookie Path and Cookie Domain blank.