Yeah, firewalls tend not to happily co-exist on the same PC. At worst, you may even find your security compromised, if two firewalls are conflicting against each other, so it's always best just to use one. What products are you actually using? Are they all in one security suites, including anti-virus, firewall, spyware and possibly spam protector? If so, you only need one. If you want to keep them both, you may have to disable some of the functions of one of them, in order to avoid conflicts, but really, it's more sensible just to have one all in one suite, then there are no compatibility issues.