I've come across this problem before. I don't think that it is a problem with the number of files or folders, but the folder depth and file name length. Windows only seems to manage 256 characters for a pathfilename combination. (program filesmetacreationsposer4runtimelibrariesetc.... takes up quite a few of these 256 before you even get to the files!). Also on Windows 9x (FAT32) there seems to be a restriction on the maximum directory entries that are allowed. (not sure about NTFS based file systems, but I've never run into a problem yet). If you are running an NT based OS (NT/2000/XP) try upgrading your disks to NTFS and it will probably cure your problem.