programs or registry files interfering with Voip calls

HIya QLs,

again a computer related problem!!!

I have a persistant problem of unclear voip call transfer through the computer while using the voip callers viz action voip, friend call etc ,even though yahoo voice and gmail talk is working perfectly. Recently i downloaded friendcall, a browser based voip caller and tried but still the same. I installed that in my another system and kept it side by side and it was working perfect. So i ruled out any problems with my net connection as well as my mic and earphone. And i concluded that something in my other system is interfering with the voip calls. as a matter of fact Itorrent could have been the culprit but i did delete the program as well. Anybody has a clue over this?.

thanks in advance

vinith