Applications freezing/error reports not sending

Question

I've had my Macbook for a over a year and probably 8 months into owning it, downloaded applications started freezing for no reason. For example - Skype and the Last.fm scrobbler... it happens every so often with Firefox also. I can open and use them but eventually they freeze anywhere from a minute to a couple hours later. Skype is famous for freezing on-screen (when it says "so and so is typing..." in the upper right corner), forcing me to restart the computer completely to be able to reopen the application. What's even worse is when I force quit the error report won't send. I've tried completely removing them and reinstalling but that doesn't work. I don't have Norton or any sort of anti-virus program, and pre-installed applications (iChat/tunes/etc) don't freeze.
Sorry if this has been answered somewhere, I haven't been able to find any help.

Answer 1

HI,
Check for available disk space.
Right or control click the MacintoshHD icon. Click Get Info. In the Get Info window you will see Capacity and Available. Make sure you always have a minimum of 10% to 15% free disk space at all times.
Freeing space on your Mac OS X startup disk
If disk space is not a problem, then try booting from your install disk and check the startup disk for errors.
Insert Installer disk and Restart, holding down the "C" key until grey Apple appears.
Go to Installer menu (Panther and earlier) or Utilities menu (Tiger and later) and launch Disk Utility.
Select your HDD (manufacturer ID) in the left panel.
Select First Aid in the Main panel.
*(Check S.M.A.R.T Status of HDD at the bottom of right panel. It should say: Verified)*
Click Repair Disk on the bottom right.
If DU reports disk does not need repairs quit DU and restart.
If DU reports errors Repair again and again until DU reports disk is repaired.
When you are finished with DU, from the Menu Bar, select Utilities/Startup Manager.
Select your start up disk and click Restart
Carolyn