Well, here's the gist of it all.

So I've got a Dell Inspiron 6400/E1505 laptop with MediaDirect and I decided to use MediaDirect for the first time to watch somethin' while I was eating lunch.

Seeing as I dual boot between XP and Vista and deleted the MediaDirect partition earlier this year, I didn't think about it making a new partition.

So I shutdown my computer and booted up into MediaDirect. I waited a while then was met with the message on a black screen "Invalid Partition Table." So I figured, "Ah poop! Doesn't work.", and began to reboot into XP. As it rebooted, I got the same message, "Invalid Partition Table."

After a while of freakin' out, I finally realized how dumb I was being and popped in the Vista setup disc and deleted the MediaDirect partition. Then I was able to boot into Vista. I was all happy and junk until I tried booting into XP. Now all I get is a black screen after the BIOS screen and before the XP splash screen.

I've tried replacing the ntldr, NTDETECT.COM, and Boot.ini files with new ones from my sister's laptop as I have done before. I've used the XP Recovery Console and ran "CHKDSK /r" and "FIXBOOT D:\" and that didn't work either.

I'm lost! Can anybody help me out here with something besides having to completely reinstall?

Hmm... Can you look at the partition table to see if something's wrong? Try a partition editor of your choice, I would use GParted. It needs to be burned to a CD, but is one of the most advanced free partition editor's I've found. See if anything is unusual with the partitions..

Do your files show up in the partitions if you boot up with something like BartPE?
If your partitions/drives are empty, Congratulations! You have been randomly(seemingly) selected as the recipient for an:
Invalid Partition Table!!

Here's the program that I used when I had a similar problem
http://www.filerecovery.biz/
Worked perfectly. But it's 30 bucks

I've been told that this one is a good alternative
http://en.wikipedia.org/wiki/TestDisk
I haven't tried it but it's free.

When I had this problem I was so freaked out that I bought another hard drive to backup my old one.
I didn't really need it though.

Good luck!

Well since I wasn't able to get my hands on BartPE, which was a more beefed up version that Adreniline had, and I didn't really want to pay for anything, I just re-installed.

I was able to backup everything needed from Vista, so I just did that.

Thanks anyways for the advice crazytieguy and MasterSaitek009.