Removal Tool

[kosay]

hi all
can anyone help me to start build removal tool ??? any exambel
I need removal tool detect malware by its MD5 but the problem is scan function
I make function add sub files to list box and each file calculate its MD5 and when MD5 = malware MD5 it detect it as malware but when I write

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Scan("C:\")
    End Sub

program 'Not Responding' and I can't stop scan or pause it .
can anyone give me linke for exambel of Removal tool or function to scan all files and find them MD5 and can stop this function
thank you