Complicated Multi-operating System

I have a compact laptop bought second hand but has problems.

1) Firstly when it is switched on it asks to choose between either windows 98 or windows 2000 pro (the one i want to use)

2) On loading up windows 2000 it works fine however when i try to use many options such as; volume control, disk cleanup, msconfig, majority of .exe files etc it says "access to file denied" or "cannot find the file "xxx". make sure the path and filename are correct and that all required libraries are available" - this is despite the file it is looking for being the one I want to use.

3) On searching futher I noticed that in my computer along with the usual WINDOWS directory. I have 2 other operating system folders in their entirity. WindowsNT and Windows 98 - I think that having all systems on my computer must be reason for it not working

4) I have tried to uninstall windows 98 using its own uninstall program however get the message "cannont find "xxx" etc

5) I have a feeling the windowsNT is just cd contents and ahs not been setup properly and could therefore simply deleted but I ahve not done so just in case

6) If i begin the laptop ion windows 98 much more works, including sound etc, however the uninstall still does not.

7) Misc problem - I cannot install any more programs when running windows 2000.