You could try some of the following:
- Defrag the hard drive
- Look through your stuff, and delete stuff you don't need to free space
- Get more RAM
- Reinstall the dodgy programs
- Possibly reinstall your OS
- Or...* PREPARE YOURSELF FOR IMMINENT HARD DRIVE FAILURE *
Be wary of the last one. It could be that your hard drive needs to go into retirement, and this would be symptematic of this, but I hope I'm wrong. Try the other options first.