Dual Boot

I have a laptop dual booting Win 98 and Win NT Server. First Server and 98 was configured for fat16. 98 was changed to fat32 and Server was changed to NTFS. This configuration was working perfectly fine. I could boot into both OS with no problem. I loaded Oracle 8i on NT Server and when I tried to access 98 I get the message “Invalid system disk. Replace the disk and then press any key.” What could be causing this problem?