go to start - run
type
%temp%
look for sepm_inst.log file
look for return value 3 inside it
paste 15 lines above and below of it.
most of the time issues like these get resolved by installing liveudpate first and then run setup.exe
open cd1
run lusetup.exe
then run setup.exe
if it fails post the log file here
if its rolling back at configuring iis, check this
Symantec Endpoint Protection Manager installation rolls back at Configuring IIS.
http://service1.symantec.com/support/ent-security.nsf/docid/2007101209193548