Hard Drive Prob??

I have a 160GB external Western Digital Hard drive.
I heard that unplugging it by the mains with it still on MAY corrupt data on the drive.
I did this before i realised i shouldn't but the drive wasn't loading while i did it so i should be ok.
Anyway this hard drive has video on it and i was using a program called 'Divfix' to scan the videos for bad frames, i was scanning a whole load of videos in a long list and it got to the 10th video and said 'File Not Found'
I then clicked on 'My Computer' and say that 'H:' Was still there but had gone into that icon where a file has nothing to open into you know that little windows icon. Anyway i could still access the drive but couldn't play any videos and on the thumbnails view i could not see the first frame of any video on there it was just that windows logo.
I then restarted the computer because everything had froze, when i was back in windows i couldn't see H: at all in 'My Computer' so i swapped the USB socket and it found it fine so i thought it was the top USB socket so i swapped the cable back to the top and to my surprise it found the USB device fine.
I then looked in the event viewer to find this: (Under System)
An error was detected on device \Device\Harddisk2\D during a paging operation.

then i clicked: http://go.microsoft.com/fwlink/events.asp.

"Details
Product: Windows Operating System
ID: 51
Source: Disk
Version: 5.2
Symbolic Name: IO_WARNING_PAGING_FAILURE
Message: An error was detected on device %1 during a paging operation.

Explanation
An input/output (I/O) request to a memory-mapped file failed and the operation was retried.


User Action
If these events are logged regularly on a primary system drive, replace the device. Otherwise, no user action is required.



Version: 5.0
Symbolic Name: IO_WARNING_PAGING_FAILURE
Message: An error was detected on device %1 during a paging operation.

Explanation
An input/output (I/O) request to a memory-mapped file failed and the operation was retried.


User Action
If these events are logged regularly on a primary system drive, replace the device. Otherwise, no user action is required."

can someone explain this to me, lol.
Then i saw application log: (this was 4 mins earlier b4 the other error)
Windows cannot unload your classes registry file - it is still in use by other applications or services. The file will be unloaded when it is no longer in use.

Details
Product: Windows Operating System
ID: 1524
Source: Userenv
Version: 5.2
Symbolic Name: EVENT_FAILED_CLASS_HIVE_UNLOAD
Message: Windows cannot unload your classes registry file - it is still in use by other applications or services. The file will be unloaded when it is no longer in use.



Explanation
Windows unloads each user's profile and user's section of the registry when the user logs off. This message indicates that Windows could not unload the user's profile because a program was referencing the user's section of the registry. This locked the profile. The registry cannot unload profiles that are locked and in use. When the program that is locking the profile is no longer referencing the registry, the profile will be unloaded.


User Action
No user action is required."

The thing that leaves me worried is did these errors come up because the drive was suddenly randomly not recognised which caused these errors to come up whilst i was scanning the videos?
Or did the program i was scanning the videos with make the pc freeze which made windows not see the drive properly?

I am confused and worried in case ive knackered the hard drive.

Please get back to me on this as soon as poss.

cheers fellas.

The drive hasnt had any errors since then and i wouldnt know if its running slow or not because its not set to the master its just video file loaded.

 

sorry i forgot to mentuioned the top usb socket is pushed in too far..