I had a great post authored, but my connection took a dump on me(and is gonna be down until late Friday). So, I've configured my wireless bridge and I'm hopping on my neighbor's network. So much for my web site and email for a few days.
OK, back to what I remember.
Uninstall MyDMX and remove the dongle from the hardware manager. RESTART.
Re-install. See what's going on.
We have to see where the issue is. What is the OS is a typical question Jingle's starts with, which is a good place to start and I agree. But I'd also want specs on the target machine: HD(and space free), RAM, CPU brand and speed. I prefer Intel, seen too many AMD's fail. Might your laptop being underpowered?
Another hint is to NOT boot with the dongle plugged in. Just seems to work better being plugged in hot in my experience.
In some cases, stuff can get married to a port for a variety of reasons. It could be OS, hardware, software or whatever. MyDMX isn't doing this. I can use the MyDMX dongle on any of the 3 USB ports on my Macbook Pro running Bootcamp, so I don't have any port marrying issuues.
Could it be your cable? Do you have another device that uses an A-B USB cable? We need to confirm it is the cable. You've proven the dongle is OK, it works on your desktop. That's good, but the troubleshooting isn't complete. Ensure you test the dongle and cable combination to ensure a working pair if need be. I dont use the included cable as I have plenty laying around and they have all worked fine for me.
As far as Jingles saying it's a USB driver issue, I'm leaning towards that but I can't say for certain.
Other stuff to check:
Are you doing the hot plug-in for the dongle?
I'm sure you're plugging in the dongle BEFORE you launch MyDMX. I don't mean to be insulting to you, but it's just become sort of a "don't assume anything" methodology that works for me.
Let me share. Put down the drinks and go potty now.
In short, I had a client angry that his modem wasn't working. He's telling me it's plugged in, the software is fine, the lights are flashing(it's an external modem). NOTHING is getting any results and he's insistent there is something wrong with the modem. Finally, I'm frustrated, because I've run into simple issues before, so I figure "Hey, let's just start from scratch and control the scenario, even if it is insulting". So, we start basic. Is it plugged in? Oh, why, no it isn't. Well, why not? "Oh, I forgot I left it in my car". Gee, a quick trip, grab the gear, plug it in and well, guess what? It worked fine. Duh!
Again, remove MyDMX totally and then reboot. Re-install the software from the web site. Reboot, why not? Can't hurt. Leave the dongle OUT while doing this as well. When you're doing a reboot, after booting and logging in as required, plug in the dongle and ensure you see it. At this point MyDMX should run in USB mode.
The good news is you have a working configuration so you know what it SHOULD be doing. It's nice to have a control environment.