Virtual PC supports a relatively unknown feature called a ‘split virtual hard disk’. The problem here, is that if a virtual hard disk is created on a FAT32 partition on the host operating system, it cannot grow larger than 4GB in size because that is the file size limit for FAT32. In order to handle this, Virtual PC will detect if it is about to go over 4GB on a FAT32 partition and ‘split the disk’ by creating a new file (.V01) and continuing to use that (until it eventually needs to create a .V02, .V03 and so on).
The question that often comes up is ‘If I move a split virtual hard disk to an NTFS partition, how do I unsplit it and turn it back into one big file’. The answer is simple, though not obvious.
What you need to do is to edit the virtual hard disk in question with the Virtual Disk Wizard. You should then select to compact it and then compact to a new file. This will create a new single virtual hard disk file that is a copy of the original split virtual hard disk.