Hi,
Either upload logos for all manufacturers (no exception) -OR- disable the "show manufacturer logo" via Flexible VM3 Template plugin.
If some of the manufacturers don't have any pictures (logo), and the "show manufacturer logos" parameters is enabled; then you will get PHP error (which causes the white blank page)
Make sure to upload pictures to "all" manufacturers -- if you don't have any picture for some of the manufacturers yet, just upload a dummy pictures for them. To find a nice dummy picture,
see this URL
Regards.