PRB:Assemblies not getting UnRegistered during setup Unistallation

Question

hi friends, i am a facing a problem with Registering Assemblies to the Global Assembly Cache. the problem is somewhat like this. i am working on a product which has quite number of assemblies and few of them get added to the GAC. so a "setup" has been prepared. the setup successfully registers all the files in the Global Assembly Cache, when it installs the product. but the problem arises when i try to "uninstall" the product. it does not remove the Assemblies from the Global Assembly Cache, nor does it allow me to delete the registered assemblies from the GAC Manually. this creates a problem when i try to install a new setup. since it does not Update the Global Assembly Cache with a new set of DLL's. and thus creating problems for proper execution of the product. this problem does not recur on all the machines. on certain machines, it does not create any problem. any solutions to the problem are welcome. Regards Thanx in Advance. shyamal