Folders replaced by recycle bin icons

In the last couple of days, a few folders on our network at work have been replaced by recycle bin icons and we have been unable to access some of these folders. However, some folders only temporarily change to recycle bin icons and are inaccesible but after let’s say about half an hour or so they change to regular folder icons and seem fine. My only concern is that a couple of folders have not changed to normality since they acquired the recylce bin icon and are inaccesible. We have a mixed network environment at work – NT Server 4, client computers are Windows 98 & Windows 2000 Pro with FAT, FAT32 & NTFS file systems. Any solutions????