HELP error 507 HELP PLEASE

[shambasha]

i was in the process of updating my 8700 with the Baharti OS, but I wanted to start with a fresh Blackberry, so I ran Javaloader to flush the OS.
then I deleted my old Blackberry desktop.
I downloaded the Baharti OS, installed, then when I conncted the Blackberry, I can't force the New OS to load, the Desktop software can see the blackberry, but when I run the application loader it is telling me NO OS contact your system adimn
I did follow the the direction for upgrading the OS, I deleted the vender.xlm file and repleace the BlackBerry.alx

Can someone help please

[justin.culp]

Make sure you are on a powered USB port....(on DELL, rear)

[NJBlackBerry]

Locate and delete VENDOR.XML (not xlm)
ALso, make sure you have downloaded and installed the latest operating system for your handheld.

[shambasha]

powered USB was the answer, I hate my Dell.
Thank you all