Thank you Mr. Hobbs for your last solution. We have been following it.
But now we have another problem. Every time I install a modification patch of a software "XYZ" say "XYZ1.1" ,"XYZ1.2", I get entries stacked in to Control Panel->AddRemovePrograms List as installed application. Whereas each version just overwrites the old exe with new one.
Is this OK? If not the what could be solution? May we face any problem because of such stacking of entries.