There are multiple possible causes for this:
Cause 1: .NET 3.5 is installedIn this environment, they had a standard "build" procedure on their servers of installing all the latest patches, and upgrading the optional components as well. .NET 3.5 is one of those. Even though .NET 1.1.4322 was registered with IIS, simply having .NET 3.5 on the box caused this error. Having .NET 2.0 did not seem to cause the problem.
Oh, and because they were installing SQL 2005 locally, they had to upgrade .NET, and the easiest thing to upgrade to was 3.5.
In another environment, they had locked-down their Domain Administrators to not have complete local admin rights on the box. He was logged on using the Domain Admin during the install of task server and it failed.
We could tell that the permissions were insufficient as we could not access the Appliction or System event logs in the log viewer. It just showed an "access denied" message.
Ensure that only .NET 1 or 2 is loaded, and that .NET 1.1 is the only thing registered in IIS, and the installation should work fine.Resolution 2:
Ensure that the account you are logged in as has FULL Local Administrator rights before installing or repairing Task server. Also, ensure that you are logged into the NS as an RDP Session 0 (using either the mstsc /admin or mstsc /console switches, depending on what version of windows you are running locally).
Once you are logged in with sufficient access to the server, the Task Server install / repair should work fine.
NS 6.0 SP3, R11
Windows 2003, SP2 Enterprise
SQL 2005 on-box