Lightroom :: Moving Catalog From 1 Computer To Another?

I have a separate catalog of photos from a recent trip on my laptop (don't ask why I created a 2nd catalog - won't do that again). I want to transfer them to our desktop, which is a mac (the laptop is pc). Following instructions in a tim grey email, I used "export catalog" to transfer to an external hard drive, with intent to then import to the mac. I did check for it to export negative files. It took forever, but froze partway through the process. So I created a new folder to export into, and tried it again. It got much further that time but froze again. When I use lightroom to access the files that did transfer, I find the folders labelled as they are on the laptop, but when I open them, the application says, "no items match your search", although it does indicate there are i.e. 47 MG in the file. I can use picasa to view the files, both the jpeg's and the raw files, so they're in there.