Hard drive virus?

[relapse71]

I have a western digital 1T external hard drive. I plugged it in and noticed when you add up all the files on the drive, it is short by about 100G compared to the "used" pie chart (450/930G of files when looking in properties, but pie chart says 550/930 used). I have hidden files exposed. Here's the kicker. I had a laptop, but it had a hard drive failure according to Fn hold down BIOS test, so I got another computer. I plug in my hard drive to transfer files, all of a sudden the internet is slow, programs wont load, and when I try and install AVG, it never updates (I have a free trial of micro trend installed w/ the computer). I scanned the external hard drive and my computer, and get nothing. What are my options. I would reinstall windows, but my Asus didn't come with a windows disk (do I call Asus, could they help?) Any suggestions?

 

[exdeath]

NTFS meta data can take up a lot of space $MFT, $JRN, etc. $ files do not contribute to explorer file size reports but are part of the pie, as you could clearly see by looking at the pie on a freshly formatted drive.

Also directories without appropriate permissions will not contribute to properties. eg System Volume Information can have 20GB of restore points and will show 0 bytes with default rights.

 

[Concillian]

Also the block size.

Whatever the block size is, that's the smallest a file can be.
If a file is 2k and the block size is 4k, you lost 2k.
If a file is 4.1k, you lost 3.9k.
A lot of files will add up to a lot of little bitty chunks that get used without necessarily being reported by file size. The "file" may be reported as 4.1k, but the actual used space is 8k (as an example... a file could be 3 megs, but it will still have a little chunk of empty space. All files will have little chunks of empty space due to the block size.)

 

[relapse71]

It wasn't that. I transferred the files over to my laptop and then deleted the external drive. I re-transferred and now the amount of used space is correct. So, why the discrepancy before?