Software Deployment

I have an MSI that will not validate with Installshield. When I try "Full MSI validation suite" or using our custom cub file it just sits and does nothing. The MSI has hold of the validation file that is created through validating as when I try to delete the "ValidationFiles" folder it tells me that the file is in use. This particular MSI is the extracted one from "FileFormatConverters.exe" used to convert Office 2007 files for use with OfficeXP. I can validate it no problem using ORCA. I have had this before and was wondering has anyone come across it before? I am using Admin Studio 6.

thanks