Windows 7 x64 upgrade + Dell Quickset screen brightness problem

Background:

I recently upgraded my XPS 1340 laptop from Vista Home Premium x64 to Windows 7 Home Premium x64, using the free upgrade from Dell. I also followed the instructions and used Dell's Upgrade Assistant DVD, which uninstalled incompatible software (mostly Dell apps and one driver) before the upgrade, and installed new versions (Dell apps again) after. There were a couple of hiccups in the process (one driver reported successfully installed by the upgrade assistant, but Win7 reported failed, and one installer froze, so I had to end it and rerun myself), but otherwise was successful.

Here's the problem:

I can press Fn+Up or Fn+Down to change my screen brightness, and the blue overlay with the brightness meter shows up as before. However, as soon the blue overlay disappears, the actual screen brightness jumps by 1-2 notches! E.g. I can set my screen brightness to 0, and once the overlay disappears, the screen jumps to brightness 2. If I hit Fn+Down one more time to set brightness 1, after few seconds it will jump to 3, etc. If I hit Fn+Down and Fn+Up many times, sometimes it prevents jumping, or it only jumps by one. It seems random.

Eventually I just uninstalled Dell Quickset and that solves the problem -- I don't get the nice-looking overlay when adjusting brightness or volume anymore, but it adjusts normally.

These versions had the problem for me:

• Quickset 9.6.8.0 (from the Upgrade Assistant DVD A01)
• Quickset 9.6.6.0 (A00) (the only driver download online for Win7 x64 currently)

Specs:

Dell Studio XPS 13 (aka 1340)
Nvidia GeForce 9500M (9400 + 9200)
Windows 7 Home Premium 64-bit upgrade
BIOS A11