Step 1: Check to see if you have proper permissions in the registry.
a) Click Start, type regedit in the Start Search box, and then click regedit in the Programs list.
b) Locate, and then click the following registry subkey:
HKEY_LOCAL_MACHINESOFTWAREClasses
c) Right click on Classes and choose Permissions.
d) Now click Add and type the username that you want to grant permissions to under Enter the object names to select and click Check Names. Click OK.
e) Now select the username you typed from Group or user names and check Full Control under Permission for.
f) Click Apply and OK. Try installing the software again.