I wanted to slipstream WinVBlock into a USB installer of XP using nlite (so I wouldn't have to press F6 during setup) But a problem occured when trying to slipstream this driver. nlite would report "unhandled exception" and "length cannot be less than zero" However, I found a solution for this! The problem is caused by some empty space between lines 24 and 27 in the TXTSETUP.OEM within WinVBlock I found if I deleted all the space after WinVBlock64 = "WinVBlock Bus (64-bit)" and before ; iaAHCI.inf then the error goes away. So here's what to do: Open up TXTSETUP.OEM, place you cursor at the end of line 24. Press delete 4 or 5 times to remove all the empty space. Press Enter twice to recreate some empty space. Save. I hope this helps someone else as much as it helped me.