Directory created: C:\UBCD4WIN\BARTPE\I386\SYSTEM32
Directory created: C:\UBCD4WIN\BARTPE\I386\SYSTEM32\CONFIG
Copying file "C:\I386\setupreg.hiv" to "C:\UBCD4WIN\BARTPE\I386\SYSTEM32\SETUPHIV"
Error: CopyFile() "C:\I386\setupreg.hiv" to "C:\UBCD4WIN\BARTPE\I386\SYSTEM32\SETUPHIV" returned error 32: The process cannot access the file because it is being used by another process.
Opening/creating the registry hives
Removing existing hive files
Building done...
There where 1 errors and 0 warnings
Use the [<<] and [>>] buttons to jump to Error/Warning


Any thoughts?

Restart the computer and try to build again... if that doesn't resolve it... try building it in Safe Mode.