My L755 is still running fine, so I'd say the first thing to check would be your software. Of course the first thing to do would be to back up any data you don't want to lose. Then I'd boot from a repair disc and see if that helps. After that I'd run SFC. To do that click Start and type CMD in the search box, then right-click CMD.EXE and click "Run as Administrator". From the ensuing command prompt type sfc /scannow. That will run for a couple of minutes. If you still have the problem after that, I'd download disk diagnostics from Western Digital or Seagate and run them to see the status of your hard drive. You can also run a System Health Report via Control Panel -> Performance and Information Tools -> Advanced -> Generate a system health report. There's also a Toshiba PC diagnostic tool that might help.
I see you've run a registry cleaner. Uh oh! They don't help and can cause problems. That adds strongly to my suspicion that you have a software problem, so after saving your data, you will probably need to restore to factory settings.
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Good luck.
(Laptop is Toshiba Satellite L755 with 4GB RAM and Pentium 2.0 ghz processor, Windows 7 - - 64 bit)
I get the (not responding) message in EVERY program, not just my browser. It's very frustrating. I've tried 3 different browsers, and it also happens in my mail, word, excel, and other programs I use. So it's not just an internet problem.
I regularly clean caches, disk optimize / defrag, run malwarebytes, spybot, plus my norton antivirus. I read about possible temp problems, so I ran a utility for that, and temp is not an issue. I constantly watch CPU and memory usage, and those numbers are good.
I'm at a complete loss and ready to just trash this laptop and get a new one.

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