Hi Toddrhind,
Sounds like the operating system is locking up or at least the HDD may be having trouble.
I'm assuming you are running Windows XP or Win7? If so, run the following instructions:
1. Click on START and choose RUN
2. Type "CMD" (without the quotation marks) and press the enter key. This will open the command prompt.
3. At the flashing cursor, type "CHKDSK /R" (without the quotation marks) and press the enter key. It will say :
The type of the file system is NTFS.
Cannot lock current drive.
Chkdsk cannot run because the volume is in use by another
process. Would you like to schedule this volume to be
checked the next time the system restarts? (Y/N)
4. Press the "Y" key and then press the enter key.
5. Now restart the computer.
Check Disk will run when Windows restarts and will run 5 different checks on the hard drive. Here is a link to the explanation of what this program does
http://support.microsoft.com/kb/187941
In a nutshell, chkdsk /r will check the file system, partition tables, Operating system files etc. If it finds any inconsistencies and can repir them, it will.
This program can take a while to run depending on the size of the hard drive and what problems it encounters.
Once the program finishes the computer will continue to boot to Windows and you can log in as normal.
Straight after CHKDSK is completed, run "Disk Defragmenter" to tidy up the files on the HDD.
This is the first step in troubleshooting this type of system failure.
Let me know how you go.
Cheers,
Rob