i get a aim dcc window

i have a little problem, every so often i see a Aol Dcc window pop up then quickly dissapear, but it makes a trillian message type noise when this happens (i do not have trillian installed and have never used it on this os), it basicaly just flashes on my screen fast enough to see what it is but i am unable to see who the request is from. i have Norton and i also use Panda online scanner, Ad-aware se pro. i dont normally open up the Ad-watch beacuse i always forget . last time this happened i opened Ad-watch and it said there was a registry change for my "current version" and also a registry change for my aim.exe, i am unsure of what the current version was. but i blocked both actions, after this i ran the Ad-aware and then both my norton and the online panda scanner, nothing came up with any of the scans. i have a linksys router and no firewall

my question is should i use any addtional software to prevent this or to check if my sytem is clean? i have run a few diffrent software firewalls but i uninstalled them cause i thought they were quite annoying . all suggestions are appreciated thanks in advance - Omni

Check to see if your system is clean, There is always a chance you have a trojan, Install something like Zone Alarm (free) and watch what is trying to access you from the 'net and what is trying to get out. This might give you some clue what is running then you can check processes find what & where it is.