My computer is running Windows 7 operating system with 4 GB RAM and Core2Duo processor. Actually, I have done an upgradation to this particular operating system recently. Everything was fine in the previous operating system, that is Windows Vista. After upgradation, the weird problem that has struck my system is that it can't find Xvid codec in Virtualdub. I am not able to get why this problem is happening because I have installed the codecs properly.