Windows html help

Hi, I'm trying to open some help manual in some applications (using "Windows html help executable" as default). It used to be ok, but now, if like I try to open the help file "artitle.chm" in windows help folder, it give me this kind of message (titled Help): "Cannot open the file: mk:@MSITStore:C:\WINDOWS\Help\article.chm". Do anyone out there what the problem is and how to correct it?