Option 1 (If you are in "Safe Mode").

1. Click Start > in the Search/Run box type cmd {enter} then type the following,

REG ADD "HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal\ MSIServer"/VE/T REG_SZ /F/D"Service" {enter}

2. Then type in the following,

net start msiserver {enter}

Option 2 (If you are in "Safe Mode").

I had a problem doing this with a Windows 7 machine the other week. So instead I simply ran the following .reg file

Allow install in safe mode.

Which if you want to take a look does this:

Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal\MSIServer] @=”Service”

Then manually started the installer service:

net start msiserver

Option 3 (If you are in "Safe mode with Networking").

1. Click Start > in the Search/Run box type cmd {enter} then type the following,

REG ADD "HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Network\ MSIServer"/VE/T REG_SZ/F/D"Service" {enter}

2. Then type in the following,

net start msiserver {enter}