How Can You Fix - Access denied to optical drives, A:\, external (USB) HDD, camera and flash cards.?

Access denied to optical drives, A:\, external (USB) HDD, camera and flash cards.

After ~ three years great performance with XP Pro on this machine, have suddenly lost access to optical drives, A:\, external HDD, camera files and flash cards.  All these are plainly visible in "My Computer", but "access denied" is displayed if any is clicked.
Unaware of any specific action that brought this on.  Trubleshooting each drive shows device is "working properly"
Tried restoring system to a number of earlier date points, to no avail.
Have been using a Registry cleaner for two years with good results, but have been told these can cause problems.  In fact I suspect a line (or two) is missing from the Registry and possibly inorrect permissions for the affected drives.
Does anyone recognise this fault and is there a relatively simple cure?
Thanks.

Solutions to the Problem Access denied to optical drives, A:\, external (USB) HDD, camera and flash cards.

Download SmartPCFixer to Fix It (Free)

Manually editing the Windows registry

Manually editing the Windows registry to remove invalid MACHINE_CHECK_EXCEPTION keys is not recommended unless you are PC service professional. Incorrectly editing your registry can stop your PC from functioning and create irreversible damage to your operating system. In fact, one misplaced comma can prevent your PC from booting entirely!

Caution: Unless you an advanced PC user, we DO NOT recommend editing the Windows registry manually. Using Registry Editor incorrectly can cause serious problems that may require you to reinstall Windows. We do not guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

To manually repair your Windows registry, first you need to create a backup by exporting a portion of the registry related to MACHINE_CHECK_EXCEPTION (eg. Windows Operating System):

• Click the Start button.
• Type "command" in the search box... DO NOT hit ENTER yet!
• While holding CTRL-Shift on your keyboard, hit ENTER.
• You will be prompted with a permission dialog box.
• Click Yes.
• A black box will open with a blinking cursor.
• Type "regedit" and hit ENTER.
• In the Registry Editor, select the Error 0x9C-related key (eg. Windows Operating System) you want to back up.
• From the File menu, choose Export.
• In the Save In list, select the folder where you want to save the Windows Operating System backup key.
• In the File Name box, type a name for your backup file, such as "Windows Operating System Backup".
• In the Export Range box, be sure that "Selected branch" is selected.
• Click Save.
• The file is then saved with a .reg file extension.
• You now have a backup of your MACHINE_CHECK_EXCEPTION-related registry entry.

Another Safe way to Fix the Problem: Access denied to optical drives, A:\, external (USB) HDD, camera and flash cards.:

How to Fix Access denied to optical drives, A:\, external (USB) HDD, camera and flash cards. with SmartPCFixer?

1. You can Download Error Fixer here. Install it on your system. When you open it, it will perform a scan.

2. After the scan is finished, you can see the errors and problems which need to be repaired.

3. The Repair part is finished, the speed of your computer will be much higher than before and the errors have been removed. You can also use other functions in SmartPCFixer. Like dll downloading, junk file cleaning and print spooler error repair.

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