What do you mean by special apps? You mean like xfire? Make sure you don't have anything else running in the background, such as:
Get Right
DU Super Controler
Macro Toolsworks
Girder 3.2
PRTG Traffic Grapher
MS Office: ctfmon.exe (rarely)
CyberCorder: cybrcrdr.exe
Paessler Router Traffic Grapher: prtg4.exe
3dnasys.exe
mIRCStats
[possibly] PeerGuardian
iTunes
Realtek Audio

There may be processes running that you don't realize, try cleaning out your processes, there are tutorials out there for it.