Yesterday my wife's laptop (Toshiba Satellite L755 with Intel i3-2330M, Win7 Home Premium SP1 64 bit, 4 GB RAM) suddenly went SUPER slow (somewhere between glacial and tectonic). The first odd thing I noticed was that the disk drive light was on steadily vs. the normal flickering. After Windows finally loaded and her desktop was accessible, I opened Task Manager but did not see anything odd, except that CPU usage was basically zero and Physical Memory was flatlined around 33%. Was finally able to do a quick scan using MS Security Essentials, but nothing was found. Tried to open Explorer to get additional tools (Avast and Malwarebytes) but cannot - keep getting "not responding" message. I did a restore to a few days ago but no CHANGE in performance.

She tells me that she had not clicked on any unfamiliar links in emails or web pages.

I'm at the end of my limited knowledge, so am seeking help.1) Why did you do a "restore"?

2) HOW did you do a "restore" (step by step please - EXACTLY what did you do)?

3) What happens when you boot to safe mode?Thanks for responding. Answering your questions:
1) I did a system restore thinking that since the computer was working OK the day before, there might have been some update that either did not completely download or install properly.
2) I used the windows system restore utility VIA the control panel. I selected the recommended restore point, which was a windows update done about two days earlier. It seemed to execute without problem. To note, the slow down occurred before I did the restore and did not improve afterwards.
3) I have started up the computer in safe mode as well as safe mode with networking. A "Windows Help and Support" window tries to open, but after many minutes of "Getting Help content" (no movement of progress bar) I end up canceling. No change in speed accessing files, etc.

Last night while trying to use this computer I noticed in the lower right corner of the screen the following:
Windows 7
Build 7601
This copy of Windows is not genuine.

However, the copy is genuine (original installation when purchased) and have not seen that message before. Shut unit down and started back up this morning and the above message was not present.Please do the following:

1) right-click on a command prompt icon and open as administrator. In the command prompt window type: chkdsk /r (then press ENTER). You'll be told the disk is in use and asked if you want to run checkdisk on the next boot. Say yes, exit the command prompt window, and reboot.

2) Run sfc /scannow ( http://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html )

3) Run full system scans with BOTH your anti virus app and with MalwareBytesI am happy to report that this laptop is now operating normally! . Thanks, Allan!

Here is what I did and what happened:

1) Did full scans using MS Security Essentials and Malwarebytes, both in safe mode. MS found "Exploit: Java/CVE-2013-2423" and Malwarebytes found about 30 items with names STARTING in "PUP.Optional..." I removed everything, but when I rebooted the speed was the same (S L O W).
2) Ran chkdsk /r, which found and replaced bad clusters in one file. Nothing else noted. After restarting, I noted that the computer seemed to be responding normally.
3) Ran sfc /scannow which did not find any integrity violations.

Again, my heartfelt thanks to Allan for the help.You're very welcome. Glad it's all sorted out