Getting the following error:
The installer was interrupted before Application could be installed

If you want to trace the installation error you can do the following:
Open a command prompt and execute the following command:
\windows\system32\msiexec /i installer.msi /l* vx log.txt

view the log.txt file
(the following was part of the error I got)

INFO   : [07/27/2010 09:27:59:127] [SetTARGETSITE                           ]: Custom Action is starting...
INFO   : [07/27/2010 09:27:59:127] [SetTARGETSITE                           ]: CoInitializeEx - COM initialization Apartment Threaded...
ERROR  : [07/27/2010 09:27:59:128] [SetTARGETSITE                           ]: FAILED:    -2147221164
ERROR  : [07/27/2010 09:27:59:128] [SetTARGETSITE                           ]: Custom Action failed with code: '340'
INFO   : [07/27/2010 09:27:59:129] [SetTARGETSITE                           ]: Custom Action completed with return code: '340'

The SOLUTION:
go to “Control Panel" -> "Programs and Features" -> "Turn Windows features on or off” -> "Internet Information Services" and enable all tickboxes under "IIS 6 Management Compatibility"

for procedures

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'') AND type in (N'P', N'PC'))
drop PROCEDURE
go

for views

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = 
OBJECT_ID(N'[matching].[workingset_patient_episodes]') AND type in (N'V'))
drop view [matching].[workingset_patient_episodes]
go

COPY %windir%\filename a:

SETLOCAL
..... set vars only local to batch file
ENDLOCAL

START .....
/minimized or /m
/maximized or /max
/restored or /r
/wait or /w

IF EXIST some.txt COPY c:/some.dll %windir%/SYSTEM/some.dll   (IF NOT EXISTS)

IF ERRORLEVEL 4 ERASE trashfile.tmp /P

IF %M%==1 GOTO SavedIt
:SavedIt

FOR variable in (set list) DO command .... or DO ( ... commands ... )
FOR %%D in (SYSTEM, COMMAND, SHELLNEW, "Start Menu") DO DIR "%windir%\%%D" /W

SET /P M=Type 1, 2, or 3, then press ENTER:
IF %M%==1 GOTO EXPORT
IF %M%==2 GOTO IMPORT

dir /s /f (recurs, files only)