Windows Management Instrumentation Service is disabled, causing a program error.

Recently, when I was doing an exam software, I used a section of hard disk serial number extraction in the Registration Section. Code The Code is as follows: Public   Static   String Getmainharddiskid ()
{
Managementobjectsearcher searcher =   New Managementobjectsearcher ( " Select * From win32_physicalmedia " );
String Harddiskid =   Null ;
Foreach (Managementobject Mo In Searcher. Get ())
{
Harddiskid = Mo [ " Serialnumber " ]. Tostring (). Trim ();
Break ;
}
Return Harddiskid;
}

There is no problem after testing on the local machine. When the software is sent to the user, many users cannot register by phone, so the above Code is located.
After several twists and turns out, it is because the Windows Management Instrumentation Service of the operating system has been disabled and everything is normal.