The following have been found as reasons for this issue:
1. "Integrated Windows Authentication" was not set on the Default website.
2. Domain account was blocking the Altiris services.
3. "IIS Manager > Default Website > aspnet_client > Properties > Directory Security > IP addresses and domain name restrictions" Localhost was denied access.
4. IIS’s script maps (IIS metabase) are most probably not right.
Here are the resolutions to those causes:
1. In IIS Manager go to Default Web Site right click and choose Properties. Click Directory Security tab, click Edit on Authentication and access control, check mark the box Integrated Windows Authentication and click OK. Click on Web Site tab and check mark Scripts. Restart IIS
2. Re-enter the password for Altiris Services.
3. Grant Localhost access to the aspnet_client virtual directory.
4. Aspnet_regiis is located in the C:\windows\Microsoft.NET\Framework\v1.1.4322 directory. Some hints:
Notification Server 6.0.x