If you're installing ISA 2004 SP2 on a mixed environment when ISA Services in Workgroup and ADAM in Domain, you may get this installation failure.
Error 1603: Setup failed while registering new events and alerts. Refer to the KB article of this update for support
To resolve this use the following workaround:
1. Let's say ISA machine is logged on with ISA\MyAdmin
2. On the ADAM machine create local user MyAdmin with the same pwd as ISA\MyAdmin, add it to the local administrators group.
3. Add ADAM\MyAdmin to the ISA enterprise administrators group:
On the ADAM machine:
a. Start --> programs --> ADAM --> ADSIEdit
b. Connect to port 2171, DN: CN=fpcconfiguration
c. Expand fpcconfiguration, cn=Roles
d. Right click on CN=Administrators--> properties --> double click on "member"
e. Change the "Locations" to point to the local machine
f. Add your local user (MyAdmin)
4. Run SP2 setup on ISA machine logged on as ISA\MyAdmin
5.Remove the account you created in step #2
Microsoft Knowledgebase article 246071 Description of Symmetric and Asymmetric Encryption