I have two Zen Cart sites hosted on my reseller account with Hostgator, which recently was moved to a new server. One domain has a unique IP and their own SSL cert, the other one isn't using SSL at all.

Both sites have reported problems with users logging in. They enter their username and password and it just takes them back to the welcome page with no error, but they're not logged in. I wasn't able to duplicate the problem with either site. One client was able to duplicate the problem on two of his PC's, but the third one worked ok. That got me to thinking it was cookie related.

So I had him delete the cookies for the domain and then it worked. So that's good, but not every customer is going to know they need to reset their cookies, nor how to reset them.

Is there any setting I can make that would force Zen Cart to delete any cookies for the domain and start fresh?

Any idea why moving to a new server (same domain name but different IP address) would mess up cookies?

Here are the current settings I have:

Cookie Domain True
Force Cookie Use False
Check SSL Session ID False
Check User Agent False
Check IP Address False
Prevent Spider Sessions True
Recreate Session True
IP to Host Conversion Status true
Use root path for cookie path False
Add period prefix to cookie domain True