GRUB problem when deleting one backtrack failed installation partition

Hi all!

I have Windows 7 and via Wubi I installed Ubuntu on my netbook (Acer Aspire One).

Then, I wanted to install Backtrack4 to use it from the hardrive. I tried to install Backtrack 2 times, and the second time the installation was OK... but the first installation was interrupted, so I got one partition with no backtrack working on it.

I tried to erase the partition with gpart and my troubles began. Grub errors. I used Super Grub Disk and I finally made Windows and Ubuntu work OK (vía wubi-windows bootloader)... but I can't get into Backtrack.

Is there any posibility to make the Windows Bootloader to start Backtrack?, I have tried with EasyBCD but I could't find how.

Thanks!!

Jano