Problem with cookies

[fogelda]

I have the following problem – I’ve developed a site (php) and there is a simple login form, which sets a cookie. In Windows it works fine, both on Firefox and IE9. On my customer’s Mac it the cookie is not saved (checked with Safari and Firefox). On other Mac computer it works fine. The problematic computer runs Mac OS X version 10.6.6
I guess it’s something about privacy settings, although we’ve checked Firefox settings and they allow cookies.

Any idea what can I check/do?

Thank you in advance.