Chuck, I'm also getting Error 1, but on a WinXPPro system:
Error creating thumbnail! Error code: 1
"e:/im6/mogrify.exe" +profile "*" -size 100x75 -quality 70 -geometry 100x75 -unsharp 10 E:/www/cabletv.com/photopost/data/1/thumbs/armacost020.jpg
I did try changing to single back slashes, but PP automatically converted them to double backshashes.
Help will be appreciated.