[Wine] What is a clean WINEPREFIX?

[ToddAndMargo]

Hi All,

I am getting:


> wine: cannot find L"C:\\windows\\system32\\wineboot.exe"
> err:process:start_wineboot failed to start wineboot, err 2


And am being told to: 

> Use a _clean_ WINEPREFIX for installation.


And, also being told to ask you guys what the above means.

Many thanks,
-T