Magic Trackpad won't work with Magic Mouse on brand new 2011 27" i5 iMac

Question

I have a brand new 2011 27" i5 iMac which I bought with Snow Leopard pre-loaded. Naturally, I included the new Magic Trackpad in my purchase, and though there were some problems with the device in SL - such as it going haywire without explanation - it generally worked, although battery levels were erratic (one day 80%, then an hour later 42%, then 80% again).
When I installed Lion I did a clean install after backing up to Time Machine - and a Super Dupered external drive. I had some difficulties trying to install Lion from an external flash drive so I deleted again and reinstalled SL, then reinstalled over the SL install I did (with no other software except Mac OS X 10.6.8 and other system updates to facilitate install). Rather than copying apps from my old SL drive, I downloaded fresh copies and reinstalled one by one. I don't use a lot of apps apart from Microsoft Office, browsers and iLife and have not installed any additional scripts, extensions or add-ons (like USB Overdrive). It's a pretty clean install.
Since then, although I'm generally happy with Lion, the Magic Trackpad won't work! It does work for a little while with basic gestures - mainly moving the cursor and scrolling - then it gives up the ghost and loses connectivity. I have done the following:
Disconnected and reconnected the MTP after turning it on and off. MTP works for about two minutes, goes crazy then no response.
Shut the computer down, pulled out the plug, waited two minutes, then started up again. MTP works for about two minutes, goes crazy then no response.
Run Onyx, shut down computer, then pulled out plug (see above).
Checked options in Universal Access, shut off "Ignore other devices when trackpad in use" (or whatever the option is). MTP works for about two minutes, goes crazy then no response.
Turned off the Magic Mouse. MTP works for about two minutes, goes crazy then no response.
But none of this seems to work! I know the MTP is connected because I can see it in the BT menu in the menu bar and also in System Preferences. I have noticed since upgrading that my permissions - which when I bought the computer were totally clean - now run lines and lines about "Library/Core Services" so I am unsure whether this is related. I also notice a lot of people are in the same boat as me, which makes me wonder if it's either a hardware issue or a release issue - after a week or so of totally silent running, my 2TB Hitachi HDD started up with the grumbly tum. I'd really appreciate any tips from anyone out there!

Answer 1

Hi, marksaner
You could try installing the latest version of the Synaptics driver. Synaptics is the company that makes the UltraNav driver and drivers for many other computer brands. This driver should have the same functionality as the UltraNav driver, so there's no worry there. You can find the driver here. 
Hope it helps,
Adam
Did someone help you today? Press the star on the left to thank them with a Kudo!
If you find a post helpful and it answers your question, please mark it as an "Accepted Solution!" This will help the rest of the community with similar issues identify the verified solution and benefit from it.