I have just purchased a brand spanking shiny new 2.66 GHz, 350Gb MacBook Pro 17" with OS X 10.5.7.
Everything works like a dream.
I`ve done "Software Update" so all the Apple software, pre-installed, is up to date.
I`ve just loaded the latest EX Clip Browser from Sony-v.2.5, and loaded the SxS Driver into the system too.
My Sony SxS Cards faultlessly mount on the desktop when inserted into the MBP ExpressCard slot.
However, the MxR ExpressCard/16GB SanDisk and 16GB Transcend don`t mount-there`s no icon, nothing!!
Using the USB-ExpressCard Adaptor Cable mounts the MxR Cards fine but my colleagues who also use MxR Cards, say they can use both SxS and MxR Cards in the conveniant MBP ExpressCard Slot.
My MxR Cards have been used for many months in full broadcast production with no problems whatsoever and I can easily, and faultlessly transfer files into my iMac with the USB Adaptor Cable but I would expect that the ExpressCard Slot on the MBP should recognize the MxR Cards as ExpressCards?!!
Is there a way to uninstall the SxS Driver to test if there is a conflict issue?

How frustrating.

can't help other than to say my MxR readers work fine with my Transcend 16gb SDHC cards on my 1 month old MBP 17.
I didn't need to load any drivers to do this.

Have you tried more than one reader?

I had the same problem. In the end I just reformatted my mac. I installed Final Cut, XDcam Transfer, Clip browser and all the drivers. I ran a system update on everything and the cards mounted.

you had to reformat your mac???? I thought that was only a win thing??

I don`t think i`ll go that far!
There must be a way to make the Mac recognize and mount the MxR Adaptors.
It is essentially just an ExpressCard after all!

I have tried numerous MxR Adaptors with the same SDHC Cards I`ve been using faultlessly for months with them.

I don`t think i`ll go that far!

A long shot, but the following seems to have done wonders for a few of us that were having problems upgrading to FCS 'new'. Simply run a 'fix permissions' using disk utility. Yes, it's tantamount to waving a rubber chicken over the hard disk, but then again, I keep a rubber chicken handy just in case.

I was having the same problem on my 15" MBP. Just ran verify disk permissions on the MBP's hard drive. Problem solved. Thanks for the help!