Regarding the system restore as well, it gives me the following message: "A volume shadow copy service component encountered an unexpected error. Check the application event log for more info. (0x80042302)"
It looks like the Restore points got corrupted. I have tried R-Wipe&Clean program. It deletes Restore points without any warning. There is another program East-Tec Eraser and it warns before deleting the Restore points. I am not sure about CCleaner.
I don't see the _MachineThrottling on my computer. I am so sorry, it's hard ATM for me to come up with a definitive fix for this. I may have to reconfigure Windows.
travelingig I am coming round to believing that ccleaner was not the cause of your problem, you say you didn't see a prompt to back up the registry so you may not have even done a registry clean anyway. You had problems even before you ran ccleaner you say.
if you read the pages DennisD linked to they have the same problems but there are many different causes. Windows seems to have gotten itself in a twist in your case.
Did you make a system repair disc when you first got the computer?
Have you tried running a system file check? (option 2 in below link)
Just to add to the guys above, have you had a look at the "Event Viewer" to see if anything relevant was flagged at the time this issue started.
You can find and launch Event Viewer by opening the Control Panel, accessing the System and Security category, selecting the Administrative Tools item, and double-clicking the Event Viewer icon. However, you can also simply click the Start button, type Event in the Start Search box, and press Enter once Event Viewer appears and the top of the results display.
How big a deal would it be to fix it with a Windows reinstall?
Do you have programs you couldn't easily replace, as all your personal data could be backed up assuming you have other storage options.
Is it a business or your home computer?
I'm thinking that if you had to reinstall as a last resort, we could then steer you in the direction of making an "Image" backup of your System and/or other drives.
We could help and advise you how to be prepared for any future serious issues, which will enable you to easily recover from them.
In that case see if you can wheedle out any possible suspects in way of patches/software updates/software installs etc, and first have a look at the other guys suggestions above.
And of course the Event Viewer at the time the problem started.
Just as a future option, you may like to check with the vendors of any commercial software you have about re-installing and activating. This should really be no problem.
And of course, with some exceptions, there is usually free software available to rival or even out perform their commercial equivalents, and the guys on here would be happy to point you towards the best available.