Laptop series of errors- Want to understand why and how to fix

So the past few days ive noticed my laptop starting to suck more and more.

It appears the Wireless Connection app that loads at the beginning lags extremly bad. And the animation icon doesnt work. But after waiting about 5 minutes the app works(a process that should take no longer than 4 seconds)

Another thing that happens. The battery control(power control) app doesnt work anymore, I have to wait a bit until the OS fully loads and then access it through control pan in order for it to work.

The last thing. When I try to uninstall/install certain programs like Ad-aware or the HP update program I get an error saying

"Theres a problem with the Windows Installer Package. A script required for this install to complete could not be runned. Contact your vendor"

so what steps have you taken to diagnose your computer? Have you ran a thorough chkdsk on your hard drive? This would be the first place to start, then work up from there....