But, about your problem, I never even though ThreatFire as being an antivirus, but if this is the case, it explains the conflicts with avast and other programs.
I found that there is this misconception that conflicts occur mainly because they are products of the same software class (e.g. between two antiviruses, between two firewalls etc) and that everything is fine if you use security software that you consider functionally different or that "doesn't overlap".
The theoretical problem with this idea is that as one becomes more aware of security software differences, and becomes better at distinguishing security software functions, one starts to think one can combine more and more. which makes very little sense if you think about it.
For example if all you had was a vague idea about "HIPS", you would just use one. Then you read maybe that castlecops page about "different class of security software", and you start using sandboxes and behavior blockers... Then someone tells you behavior blockers actually comes in 2 types... and you use them both because they are in "different class" and hence there is no overlap and hence no conflict...
The practical problem is this.
My own experience testing is that the possibility of conflicts between security software is very high even if they are supposedly of different types. A firewall can and does easily lead to negative interactions with antiviruses for example despite the fact that one is a firewall and one antivirus.
And by negative interaction I don't just mean blue screen errors, because these at least are easy to figure out. By that i mean they were fail to stop whatever they normally would if they were run individually.
The problem is even worse with hips-type software like threatfire, online armor, sandboxes etc etc
I have tested the following combos,
Comodo pro firewall 3 + threatfire
Online armor free +Threatfire
A lot of people are running these 2 combos because these are free products and by reading the descriptions you can make a case that they cover different areas. For example threatfire is a "smart behavior blocker" while OA and comodo's defense+ are "classical hips".
A simple test finds that running both combos results in a system where neither is able to block certain keylogger techniques. On the other hand, running any one of them alone will give you better results against keyloggers!!
In other words, adding more reduces your defenses! The user will never know since there is no error message, no crash etc.
And this is just one simple test. How many other negative interactions are there that one never notices?
I would add that many people are running even more by adding sandboxes.
Combos like
Comodo pro firewall 3 +Geswall + threatfire + antivirus or
online armor + sandboxie+antivirus etc
are not uncommon, because "they don't overlap"
