Self-evidently, $objWMI is undefined - as the error tells you. You may glean more info if you change

my $objWMI = Win32::OLE->GetObject("winmgmts:\\\\$strComputer\\root\\c
+imv2"); # or die "Failed to create object";
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to read

my $objWMI = Win32::OLE->GetObject("winmgmts:\\\\$strComputer\\root\\c
+imv2");

die "GetObject(winmgmts:\\\\$strComputer\\root\\cimv2) failed - " . Wi
+n32::OLE->LastError() if
    Win32::OLE->LastError();
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i.e. when OLE fails, get it OLE to tell you why it hasn't worked.

.oO(Given the context, using CPI::Carp may also prove useful)

Update:

Modified error report to give a string.