Programs won't open after being installed

Hey there,

I am having the problem of, after seemingly-successfully downloading a
program (the two I've had trouble with so far are AIM 6 and McAfee Virus Scan
8.5i), I can't get them to open.

When attempting to open them through the Programs menu or from the desktop,
the computer acts as though it is in the process of opening the program, and
never sends me an error message, and yet the programs never open or appears
in the "Task Manager" as a program that is running/open.

HELP!

Take care,
Emma