Slow menus, Windows Explorer freezing

If anybody can give me some advice on this, it would be greatly appreciated.

I’m running Windows 7 on my laptop. For the last week, I have experienced the following problems:
- Right-click on files, menus, etc is delayed about 15sec
- Firefox will freeze any time I click on something (same with IE)
- Computer will freeze when opening any program and most won’t load, like iTunes)
- Folders on desktop will disappear randomly, and reappear a few seconds later
- Entire screen will turn white, including Windows menu bar

When I turned my computer on one time, it began something I believe is a CHKDSK, but this did not seem to do anything. Again, the computer did this by itself upon startup, I did not do this manually.

*** I also cannot get my laptop to recognize an external HDD…If someone could tell me how to do this (in safe mode, or something) I could just save the files I need and restore the computer)

Thanks anyone who can help

Hello, and welcome to the Windows 7 Forums

Have you tried Defragmenting? First run Disk Cleanup, followed by the Disk Defragmenter.
Have you recently made any hardware change to your PC? What about software?