>Sergey,
>
>>It sounds like the Windows page swap file. If you have a free space on the D drive you can move it there.
>
>Turns out that, using Windows default, the swap file is already (and always was) on Drive D, as far as I can tell, (Norton's Speed Disk reports it that way, anyway).
>

Jill,

That does seem strange. I wonder what it's storing on C: if it's not the SWAP???
. . . and TEMP space is minimal???????

I wonder if one of the startup apps could be using the space "temporarily" but putting it somewhere other that the normal place?

good luck. I'm at a loss.