I use IE 5.5. I think I have to place Infopop forums that I post to in the trusted sites zone (security level medium), not sure. I normally browse with security level high.

I use Zone Alarm Pro 2.6.362 as a firewall (for now), with no special reduced security settings required for Infopop sites.

I also use the browser filter Proxomitron, which gives a much finer degree of control over browser input/output. I may have had to relax some of Prox's settings for Infopop forums, such as allowing cookies.