What are your settings for the virtual machine you're installing leopard into? Some devices that never appear in "pure macs" could potentially cause a virtual mac to crash, or KP.
You may also consider being careful about what is plugged into your mac while installing the virtual machine. It's not likely to be the case, but if you have an external drive plugged into your laptop which happens to be an OS X bootable drive WHILE you're installing a Leopard VM, I could see that might confuse things a bit.
Most importantly, check your RAM settings for both your Mac and the VM. - In this same line of thought, consider shutting down all other programs while installing Leopard into a VM.
Is your VM trying to install to a IDE disk or a SCSI disk? are the drives split-up, allocated all at once, one big VM file?
I suggest using one big VM file with regular maintence to make for a happy host, and happy guests. Also I find that non-windows OS can be happier if they're installed on Virtual SCSI discs, NOT IDE. That is only my experience, I'm not sure why they'd care exactly but it seems to be the case.
Good luck.
P.S. here's an idea
Install Leopard Server as the Host OS on the laptop, then use VMware inside Leopard Server to install regular Leopard (when it becomes avaliable if it isn't an option already)
Also, never forget that it's important to consider your original task. If you're just trying to share files with a mac, there are MUCH easier ways to do this. What is the reason for which you're installing Leopard Server to begin with?