Cannot read D drive and F drive

I have win 98 on C drive and win 2000 on D drive. The problem started when my brother installed win WP on F drive. The installation was successful.

When I log in Win XP, I can read C drive and D drive from the command prompt.

When I log in Win 2000 pro, I can read C drive and F drive from the command promt.

But when I log in Win 98, I cannoot read D drive and F drive.

The error say “NOT READY READING DRIVE D”.

When I try to access F drive it says “INVALID DRIVE SPECIFICATION”.

Moreover,I cannot see F drive in my computers. And when I try to access D drive from my computers, it fails.

What is the appropriate solution for this?

Has some DOS files got corrupted?

Has WIN XP not been installed correctly? If this is the case then should not have accessed even from Win 2000 pro.