I would strongly advise against attempting to disable it as it is designed to protect you. Usually when it pops up it means that Windows will not be able to run normally/stably if you proceed without opting to have Vista fix it, which is an option. My advice is to let it do it's job and then try to determine what triggered it, preventing the problem from occurring instead of ignoring it.

In this case, I would suggest:
1.) Uninstall Norton and the other "stuff." Some security software scans for the presence of competing products it may conflict with and fail to install properly, causing a problem.
2.) Install the applications one-by-one to determine which one is causing the 'problem.'

John