Losing cookies when switching Joomla settings

[royc2]

Have a voluntary organisation website on Joomla 1.0 with Fireboard forum. Inundated with spam, found that by switching the Login settings from 'Registered' (ie registered members) to 'Special' (ie administrators) access for one night, the spambots got killed off and the result has been no more spam. However, there is an unwelcome side effect: many of our members' machines look to have lost the cookies with their registration details for the site. They cannot see the Login panel on the Home page. With 3,000 members, this looks like it could be a mega problem.

We can solve this partially by switching the Login to 'Public' for an hour, so they can see the Login panel and log back in. Any ideas as to why they are losing their cookies and what we can do about it?

A second problem is that some log back in successfully, only to find they are logged out again on their next visit. I only have a sample of 6 of these so far, including myself, and the only common denominator is that we are all/nearly all on Macs - any idea why Macs, or is it the browsers (Safari, Firefox etc), should lose their cookies so readily and what we need to do to cement them in?

Apologies if this is in the wrong area/thread, can't see a right place on the forum for a general issue like this.

Many thanks in advance if anyone can give any insights or clues on this one.