Suddenly slow computer

Question

I was away in Israel for 2 weeks. When I came home and synced my ipad to transfer the pictures, my macbook pro has slowed so very much. It's in opeing applications and waking from sleep. It's slow in the internet as well. And it isn't constant. Rarely but once in a while, it is as fast as it used to be.
I have tried rebooting. Knowing it's more than the network, I have cleared browser caches.
Any ideas?

Answer 1

ruth:
Do a directory check. Go to Applications > Utilities > Disk Utility > First Aid. Select your HDD (manufacturer ID) in sidebar. Click Verify Disk. If you get errors you will need to boot from the install disk and Repair Disk
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 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, and report if it says anything but 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.
If DU reports errors it cannot repair you will need to use a utility like Tech Tool Pro or Disk Warrior
cornelius