Potential Incompatibility with Firewall programs
Experience indicates that at least one firewall program can create difficulties for Infra Red communication, but the encouraging news is that a recent release may have addressed the problem.
ZoneAlarm
A well regarded firewall program, ZoneAlarm, (available from http://www.zonelabs.com ) seems to interfere with some Infrared systems. Experience seems to be that ZoneAlarm, if it is running, has to be shut down, and unloaded, before Infra Red communications work. I have found that to be the case with ZoneAlarm v2.0.26 running under Windows 98 (first edition) on a laptop with built in Infra Red operating in Serial Infra Red (SIR) mode. That’s a shame, because a firewall is a useful thing to have and ZoneAlarm is otherwise a very fine program.
Recent reports suggest that ZoneAlarm has been upgraded to deal with this problem. The version of ZoneAlarm available at the time of writing is v2.1.44, and the v2.1 release notes mention addressing some problems with most infra red devices, which is very good news indeed.
One respondent has advised that Zone Alarm Pro 1.0 (a high-end version of the program) does not interfere with Infra Red.
Norton Internet Security
I have tested Infra Red via a serial adapter on a desktop machine with Norton Internet Security, and Norton introduces no conflicts.