Like you when I first started with Linux I installed ubuntu and then removed it and I got a Grub 1.5 error 21.
All you need to do is if you have a windows cd, has to be vista or windows 7 and do this.

1.Pop in CD
2.Boot from CD
3.Select Recovery Option
4.In the DOS prompt type fixmbr

then it will ask you for conformation and accept. It should resolve your issues with the booting.

Now I usually install the /boot directory on its own so this wont happen when I delete the Ubuntu partition. Try that next time when you Install it, but install it on to the internal HD.

i was getting the same problems but after reading the posts thnx! i think i got the hang of it

YAY I FIXED IT!!! i tried it this way but it didn't work, but then i found this:
1. pop in a vista/win7 cd (if your pc came preinstalled with windows and didn't come with a disk then you can get one from Here
2. boot from the cd
3. select language etc
4. select repair computer
5. partition to repair
6. select the command prompt option


now type: bootrec.exe
that will show you the options it can do
then select the option that fits your problem best (mine was fixmbr)
so in my case i typed "bootrec.exe /FixMbr"

for more info see Here



Thanks for all you guys help, i would be lost without it!!!

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