Grub Error 21
 

Hello,

I bought a new hard drive. I thought it would be clever and SAFE to install Ubuntu on the Hard Drive so that would not interfere with the internal hard drive on my laptop. It worked fine until I disconnected the hard drive. I got the "Grub Error 21" when I installed. I know how to get around it, unfortunately, I have to lug around this hard drive whenever my computer sleeps or restarts. I would like to be able to restart and boot into Windows without my hard drive connected. Is this possible?

Of course it's possible - but depends on a few things you haven't told us or may not know.
From Linux go to sf.net, get the bootinfoscript, run it from a terminal and post the RESULTS.txt it generates. That way we can see all the elements in your boot setup (no personal/sensitive data - have a look yourself).

That's a problem because I can't log into Linux now. It boots up and freezes at about 4.5%. I can reach command prompt by running in safe mode though....

Well that makes it easier. Boot your Windoze install CD and get into recovery mode to restore the MBR:
- for Vista/Win7 read this from M$oft.
- for XP read this.