Virus Attack: Unable to open drives using double click or right click...explore or open?

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To correct and solve this error, follow these steps:

Go to the start->run.
Type "cmd" (without quotes) into the Open text box and click OK.
Type the following command one by one followed by hitting Enter key:
del c:\autorun.* /f /s /q /a
del d:\autorun.* /f /s /q /a
del e:\autorun.* /f /s /q /a

c, d, e are the hard disk drives/partitions. If there are more drives or partitions available, continue to command by altering to other drive letter. Note that you must also clean the autorun files from USB flash drive or portable hard disk as the external drive may also be infected.

Again click Start->run
Type "regedit" (without quotes) into the Open text box and click OK.
Navigate to the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

>>Check if the value name and value data for the key is correct (the value data of userint.exe include the path which may be different than C drive, which is also valid, note also the comma which is also needed):
"Userinit"="C:\WINDOWS\system32\userinit.exe," <<

If the value is incorrect, modify it to the valid value data.