Anne
In your first post you wrote I can't use chkdsk.
It is most important that you can use chkdsk as many problems can arise if the file system on the disk is damaged.
Select Start, All Programs, Accessories, right click Command Prompt, and click Run as administrator from the drop down menu.. Type *cd* and press ENTER. Type "chkdsk c: /r" without the quotes and hit ENTER. Make sure you include the spaces indicated. Enter Y when asked whether you wish to run chkdsk on restarting the computer. Type exit, press the ENTER key and restart the computer.
Please run System File Checker and say if it cannot fix corrupted files:
http://support.microsoft.com/kb/929833
To troubleshoot most computer problems it helps to look at available clues in the System Information file and the Event Viewer logs. An experienced eye can pick out the needles in the haystack and see more clearly the precise nature of the problem or problems.
Please provide a copy of your System Information file. Type System Information in the Search Box above the start Button and press the ENTER key (alternative is Select Start, All Programs, Accessories, System Tools, System Information). Select File, Export and give the file a name noting where it is located. Do not place the cursor within the body of the report before exporting the file. The system creates a new System Information file each time system information is accessed. You need to allow a minute or two for the file to be fully populated before exporting a copy. Please upload to your OneDrive (formerly Sky Drive), share with everyone and post a link here. Reports in normal mode preferred. Please say if the report has been obtained in safe mode.
Please upload and share with everyone copies of your System and Application logs from your Event Viewer to your OneDrive and post a link here.
To access the System log select Start, Control Panel, Administrative Tools, Event Viewer, from the list in the left side of the window expand Windows Logs and select System. Place the cursor on System, select Action from the Menu and Save All Events as (the default evtx file type) and give the file a name. Do the same for the Applications log. Do not provide filtered files. Do not clear logs whilst you have a continuing problem.
For help with OneDrive see paragraph 9.3: