I was looking at the other thread about Error 507, but nothing was working for me, and I can not locate VENDOR.MXL in the C drive.
Can someone please help, thanks

Welcome to the forums.

What OS are you trying to install? You need to have Desktop Manager installed first. Then install the OS you want loaded on the BB, to the PC. Then locate and delete the vendor.xml.

I think you have the white screen of death

I think the main issue you are having is you are looking for the incorrect extension. It is not MXL, it is XML.

Best of luck.

c:\program files\common files\research in motion\apploader