Adware:Adware (or spyware) is a small program that is designed to show advertisements (in various form and degrees of intrusiveness) on your computer. It often reports personal information back to its owners. As a result your sense of privacy can be violated.
Mdelk.exe is a malware application that is usually downloaded and installed onto your computer by a worm or a Trojan (including Trojan.MitGlieder.GB and TROJ_MITGLIED.AA) finding its way through browser security holes. Once executed, this malicious Trojan creates a registry entry enabling it to start at every Windows boot. In addition, it will attempt to download supplementary malware applications to your computer. Mdelk.exe can be extremely harmful to your machine and therefore it is strongly recommended to remove this program upon detection.
Technical details (How to remove Mdelk.exe(pop up))