When did this start happening? (Did you install something new recently?)

When do you see the installer pop up? At startup of the computer? When opening a specific program?

What operating system are you using?

Have you scanned for spyware/adware? If so, with what?

Have you tried accessing all program startup locations, like the System Configuration Utility (msconfig), and shutting down all unneeded startup programs?

Hope this helps and let us know more.