What's up with MSE?

[Hectic]

I today scanned a hard drive via usb with Microsoft Security Essentials.
I right clicked the drive in "My Computer" and scanned away.
It found an assortment of Mabezat.B, autorun.inf and other stuff that I can't remember.

In the end it reported 1121 of the Mabezat.B virus and mostly single or low occurrences of the other stuff.

My question is this. During the scan it would show say 221 viruses found and still scanning. Then suddenly it would revert back to 91 viruses found and the total would increase again, just to decrease at a later stage.

The option to clean only comes after scan completion.

So why are these figures jumping back. Is it files that were quarantined or what is causing the figure to jump back. I have also found instances during the cleaning process where MSE reports that the file that was reported could not be found?

 

[Lycanthrope]

When it can't be fixed, I'm not sure--could be that it's a file it doesn't have removal privileges to. I'd suggest putting the hard drive in another computer so the OS can't boot and scanning it through that PC.

The numbers jump back and forth, as such, because the pop-up collapses after a while of not finding anything, then pops back up after more new threats have been discovered and the tally rises once more, until it collapses again, and then repeat

If I discovered that many viruses though, I'd back up the necessities and format for sanity's sake.

 

[Hectic]

Make sense. I did ran the mentioned hdd in an enclosure via usb.

The thing is then, can I trust the results?

After every threat is cleaned,I must then run the av again, because I can't be sure if it did actually healed every reported threat.

Thx for your input.