Adware.w32.expdwnldr is a pop-up message in your computer which is generated by Trojan (such as Zlob). When Trojan is showing this fake alert message it wants to scare user into buying Rogue antispyware products such as VirusHeat, System doctor, SecurePCCleaner or any other.
Once Adware.w32.expdwnldr installed into your computer it can hijack your desktop and show any kind of System Alert pop-up massage.