Here's a copy/paste from
http://www.annoyances.org/exec/show/article03-204
Stop Windows from saving the thumbnail cache (THUMBS.DB)
Intended For
Windows XP only
Windows XP, by default, shows the thumbnails view of certain folders,
whether you want it to or not. Even if you choose Details (or some other
view) as your default by going to Tools -> Folder Options -> View tab and
click Apply to All Folders, Explorer may still revert back to the clumsy
Thumbnails view. It does this for any folder in which it finds the THUMBS.DB
file; naturally, if you delete this file, it won't happen again.
The problem is that Windows seems to repeatedly recreate the THUMBS.DB file
automatically. Here's how to stop this from happening:
1.. In Explorer, go to Tools -> Folder Options or open the Folder Options
icon in the Control Panel.
2.. Choose the View tab, and turn off the Do not cache thumbnails option.
3.. Click Ok.
You can also change this setting in the Registry:
1.. Open the Registry Editor (regedit.exe).
2.. Navigate to
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced.
3.. Double-click the DisableThumbnailCache value, or go to Edit -> New ->
DWORD value to create a new value by that name.
4.. Enter 1 for its value.
5.. Click Ok and close the Registry Editor when you're done; you'll have
to log off and then log back on for this to take effect.
Related article: Disable the automatic display of thumbnails in certain
folders.